edible – The Garden Professors™

Ripe for the picking: Which fruits keep ripening after harvest?

“Will my peppers continue to ripen? How about my eggplants?” It is common knowledge to most gardeners (and home cooks) that tomatoes will ripen on the kitchen counter, as will bananas and several other fruits. You know that one day your bananas look perfectly ripe and the next they’re a brown mush But does this work for all fruits? We often get questions about whether specific fruits will continue to ripen after picking. And the answer is….. it depends.

One of these fruits is not like the other

The answer as to whether a fruit will continue to ripen after harvest depends on which one of two groups it falls into. These groups are climacteric and non-climacteric fruits. In short, climacteric fruits are the ones that will continue ripening after harvest and non-climacteric fruits are ones that don’t ripen after harvest.

This refers to the “climacteric phase” of fruit ripening where there is an increase in the gaseous plant hormone ethylene and an increase in respiration, which drives the ripening process. It is the climacteric fruits that will keep ripening once they’ve been harvested, thanks to ethylene. The only stage of maturity for non-climacteric fruits after harvest is…..compost.

As long as you’re green, you’re growing. As soon as you’re ripe, you start to rot. -Ray Kroc

Almost all fruits produce ethylene, but non-climacteric fruits produce them at much lower levels and do not rely upon it as the main driver of ripening. I’ll go into a bit more detail in a bit, but first – which fruits are climacteric and which are non-climacteric?

Common Climacteric Fruits	Common Non-Climacteric Fruits
Apple	Brambles (raspberry, blackberry, etc).
Apricot	Citrus (oranges, lemons, limes, etc.)
Avocado	Eggplant
Banana	Grape
Blueberry	Melon (including Watermelon)
Cantaloupe / Muskmelon	Pepper *
Cherry	Pumpkin
Fig	Squash (summer and winter)
Kiwi	Strawberry
Mango	Cherry
Papaya
Pawpaw
Peach
Pear
Plantain
Plum
Tomato

*Some evidence of climacteric ripening in hot peppers

The ripening process

Ripening is genetically programmed – meaning that it is highly dependent on processes that are regulated by genes and it specific to each species. Parts of the process are started and stopped due to the transcription and translation of genes, which are in turn controlled by signals such as chemical compounds, physiological stages of the plant, climate, and so on. These ripening processes have a lot of end results – sugars accumulate in the fruit, pigments develop, some compounds that have pleasant flavors develop while others that are unpleasant are broken down, some of the pectins in the fruit break down to make it softer, and on and on.

Tomatoes – the classic climacteric fruit

Research shows that ethylene, the simple little gaseous hormone plays a crucial role in the ripening of climacteric fruits by altering the transcription and translation of genes responsible for ripening. Ethylene is the dominant trigger for ripening in these plants. Ethylene receptors in the cells are triggered by the presence of the gas which leads to cascade effect. This is why ethylene can be introduced from other fruits to trigger ripening in fruits that aren’t ready to ripen. If you’ve heard of the tip to put an apple in a bag full of some other fruit to get it to ripen, it actually works – as long as it is a climacteric fruit.

The same ripening processes happen in non-climacteric fruit as well, but they are not dependent on the presence of ethylene. In fact, these pathways are also present in climacteric fruits – the ethylene-dependent processes are just the dominant (and faster) way that they ripen.

Controlling ripening

The dependence on ethylene for a vast majority of fruits to ripen has been used by farmers and the food industry for a long time to keep climacteric fruit more stable for shipping. These fruits are harvested “green” before they ripen and shipped unripe since they are much firmer and much less likely to get damaged in transit. These days, bananas, tomatoes, and other climacteric fruits are likely to be given a treatment that temporarily inhibits the ethylene response before harvest or shipping to extend their shelf life further. Once they’re close to their final destinations they’ll either be allowed to ripen on their own or given a treatment of ethylene to speed back up the ripening process.

What we gain in shelf-life and reduced food waste we do lose in a bit of flavor. Since the fruits are no longer attached to the plant when they ripen they don’t have the chance to transport more sugars and flavor compounds from the mother plant. So “vine ripened” fruits do have a bit more sweetness and flavor than those that are picked green. Having just gotten back from Rwanda, a country where bananas are a common staple food I can attest that the ones that ripen on the plant are much sweeter than those we get shipped in to the US – you know, the ones that will ripen next week sometime if you’re lucky. There were even some in our group that don’t care for bananas here that loved the ones we had at breakfast every morning.

One possible direction for biotechnology is the engineering of plants to alter or eliminate the ethylene ripening response to reduce food waste and spoilage. Since many genes that are responsible for ethylene production such as enzymes that catalyze the production of ethylene precursors, or proteins that serve as ethylene receptors have been identified, work is being done to develop delayed ripening by altering or knocking out these genes in a variety of crops.

Sources

Alexander, L., & Grierson, D. (2002). Ethylene biosynthesis and action in tomato: a model for climacteric fruit ripening. Journal of experimental botany, 53(377), 2039-2055.

Pech, J. C., Bouzayen, M., & Latché, A. (2008). Climacteric fruit ripening: ethylene-dependent and independent regulation of ripening pathways in melon fruit. Plant Science, 175(1-2), 114-120.

Lelièvre, J. M., Latchè, A., Jones, B., Bouzayen, M., & Pech, J. C. (1997). Ethylene and fruit ripening. Physiologia plantarum, 101(4), 727-739.

Rhymes with nārang

By Visiting Professors Dr. Charlie Rohwer and Ulrike Carlson

I’ve had this dream of doing a full academic etymological study of oranges, with the help of a second-cousin-by-marriage linguist and her historian husband. Being honest with myself, I know that’ll never happen. And also, honestly, they’d have to do all the work anyway.

But, the Garden Professor’s Facebook post about the citrus family tree revived my interest. Not for a full-blown academic analysis of the word ‘orange,’ but for a blog-friendly, factual, interesting post. So I got my linguist cousin Ulrike Carlson to edit for accuracy too.

The name given to the orange by Linnaeus was Citrus aurantium, and the only other citrus species he noted in his first volume of Species Plantarum was Citrus medica. The current taxonomy of citron is Citrus medica L., and bitter orange (or Seville orange, used for marmalade and Belgian beer) is Citrus aurantium L. According to Linnaeus, sweet orange and pomelo were separate varieties of C. aurantium (var. sinensis and var. grandis, respectively). For a pretty image of the family tree, see the National Geographic article here. Basically, it is now known that all common citrus fruits are hybrids derived from citron, mandarin, pomelo, and papeda.

The current taxonomy for sweet orange, Citrus sinensis (L.) Osbeck, clearly defines the fruit’s Eastern origin (sinensis comes from Latin for ‘Chinese’) and altered nomenclature (Osbeck refined Linnaeus’ original taxonomy). But the name given to bitter orange, C. aurantium, points to its South Asian origin, and here’s why. The Tamil (south India) word for orange transliterates to ārañcu; Sanskrit words look similar; the Persian nārang is derived from there. As the bitter and sweet orange hybrids were likely made somewhere between Northern India and Southern China, it would be expected that the European names for these fruits come from these or nearby areas too. The origin of Linnaeus’ aurantium are obvious. Aurantium is Latin for the orange tree, and aurancia is the fruit. If you say these words aloud, they all sound similar to each other, to nārang, and to the English orange.

But here’s where it gets more interesting, with a preface: the word apple has historically been used to describe any fruit that’s not a small berry. Also, bitter oranges were common in Europe before sweet oranges. In fact, when sweet oranges came on the scene in the 17th century, wealthy people built greenhouses or gardens (“orangeries”) specifically for the new, more delicious versions of the fruit.

Orangery at the Château_de_Versailles
By Djampa – Own work

My first time in the Netherlands, I noticed orange juice is called sinaasapelsap. I don’t know Dutch really, but…doesn’t that mean ‘Chinese apple juice?’ Sinaas: Chinese (sinensis); apel: apple; sap: …sap (juice)? I knew in French that it’s jus d’orange (juice of the orange), and I knew ‘orange’ in Spanish is naranja (looks & sounds a lot like orange and narang). Why would the Dutch call it Chinese apple juice? Fast forward a couple years, I’m in Denmark, and what do I see? Appelsinsaft. CHINESE APPLE JUICE…English, Dutch, Danish, they’re all Germanic languages. Shouldn’t the Germanic languages call it orange juice, like I do? Then it hits me. English is the odd duck here. The Germanic languages call orange juice ‘Chinese apple juice’. This reflects the name Linnaeus gave the sweet orange (var. sinensis, or ‘Chinese’). Best I can tell, among Germanic languages, only English, Afrikaans, and Scots gets their word for the sweet orange from the older word for the bitter orange, nārang.

*Citrus aurantium*
By A. Barra – Own work

That’s not the last word on the subject though. You can go to Italy for sweet oranges and get arance, the Czech Republic and get pomeranče (apple-orange), Ireland and get oráistí, Bulgaria and get oranzhev, or Portugal and get laranjas (aka, oranges). All words that come from nārang or aurancia. You can go to Estonia, Finland, Sweden, Norway, and Germany and get some kind of Chinese apples (aka, oranges). But even as most Italians eat arance, you’d instead ask for a partuallu in Sicily. Or you’d eat a portokáli in Greece, portokall in Albania, etc. The Portuguese, with their awesome shipping routes, imported sweet oranges from China, then grew and distributed them through Europe in the 17th century. They were a big improvement over the bitter orange (which would you rather have, marmalade from a bitter orange, or a juicy sweet orange?). So some countries called the sweet orange by the name of the proximal country they were shipped from, Portugal. Bitter oranges (AKA Seville oranges, named from where they were grown) are called pomerans (from apple-orange) in Swedish, Pomeranzen or Bitterorangen in German, pomeransen in Dutch…so it seems that when sweet oranges came to Germanic-speaking countries, the languages kept the word they’d been using for the bitter orange (calling it an orange-apple or bitter orange), and added a different word for the sweet orange, calling it a Chinese apple. This is all complicated because political boundaries have changed a lot in Europe, and languages borrow from each other. So northern Germans might still eat Chinese apples, but southern Germans might eat oranges.

Also, if you’re interested and you’ve made it this far, the color orange is so named because that’s the color of the fruit. It’s not the other way around. It’s a pretty recent color descriptor. That’s why robins, with their orange breasts, are called robin red-breast. There was no word for the color orange when the robin was first described.

Also of great interest is the House of Orange. If you’ve seen a Dutch soccer game, or been to the Netherlands, you’ll know they like the color orange. William I of Orange, basically the founder of the Netherlands, came from a principality called ‘Orange’, now in France, and the Dutch celebrate their royal family with the color of its namesake. BUT, Orange, France was named, a couple thousand years ago (before the fruit came to Europe), after a Celtic water god, Arausio. At the time, this had nothing to do with the fruit or the color. HOWEVER, since the middle ages, the crest of the French city shows orange fruit on a branch, and the crest for the German city of Oranienbaum (orange tree) has, you guessed it, an orange tree. According to Wikipedia, Oranienbaum was named after the Dutch House of Orange.

For more about how these languages are related, here’s a ‘simple’ chart.

Ray’s 2015 Tomatoes

I thought I’d share some of the new varieties of tomatoes I’m growing this year, along with some old favorites.

First up is a picture of a new variety from Dr. Harry Klee’s research at the U. of Florida called Garden Gem, along with Blush from Artisan Seeds.

Garden Gem is a new hybrid, poised to take the fresh market grocery store tomatoes on. Same disease resistance, same shipping quality, but with much improved flavor. Dr. Klee describes the research at his site:

The first step in a flavor improvement program starts with a simple question: what do people like and what’s in the varieties that people do like? In order to answer this question, we took a giant step back to “heirloom” tomatoes.

Blush has been around for a few years, an open pollinated variety with a great history of breeding, since 8 year old Alex was instrumental in choosing its parent lines.

The year that the cross that created Blush was made, Alex participated in setting up crosses for our annual winter crossing list. He chose 3 of the 19 crosses to be made that year, after the other 16 had been established (by a PhD-holding plant breeder with big plans). The striking outcome is that about 90% of the value from that year came from Alex’s 3 crosses. The progeny from his crosses continue to permeate most everything we are doing.

Both have something in common in that one of the progenitors for each is a variety called Maglia Rosa.

Note also the meatiness of Garden Gem … I think it will make a great all-purpose variety for the home gardener for canning and sauces, as well as fresh eating.

Another aspect, which you can’t tell very well from the picture of Garden Gem, is the faint yellow striping in the skin, and some later fruits that have a hint of a nipple on the blossom end.

GardenGemGreenTiger — Top Garden Gem Next Maglia Rosa Bottom Green Tiger

Next up, another Garden Gem, followed by Maglia Rosa, and then Green Tiger. See hints of vestigal “nipple” alluded to earlier in the Garden Gem.

Cute little feller … a Currant Tomato. Actually, a different, but very close relative, and source of much research and study, since it still grows wild in the Andean mountains … PITA to pick, but great “conversation piece” when used as a garnish. Solanum pimpinellifolium

We grew these as part of a variety trial a few years back … more for the novelty. But when we did a Brix test that year, it was the highest recorded.

A little odd, since the flavor is not in the least “sweet” … coulda been just more concentrated. Dunno, really.

AuntRubyGermanGreen — Aunt Ruby’s German Green Heirloom

Aunt Ruby’s German Green. One of my long term favorites. It’s a more tangy than sweet heirloom variety that stays green when ripe.

Green Zebra … an open pollinated variety bred by Tom Wagner and introduced in 1983 according to Wikipedia.

Green when ripe, and with yellow striping. Dunno why most of mine this year are exhibiting a lobed shape, rather than perfectly round.

I may have to buy new seeds next year.

Another hybrid from the research lab of Dr. Harry Klee of the University of Florida. This one is named Garden Treasure.

I don’t have any information about its progenitors, like its companion Garden Gem.

Beautiful, baseball-sized fruit. Very slight indication of green shoulders, and with the same faint yellow stripe as Garden Gem. Also a heavy fruit, very meaty.

And very good flavor. Pretty good balance between tart and sweet. I can see these being popular with fresh market growers.

I sourced the seeds from Dr. Klee’s efforts by making a small donation to his research program at the University of Florida. The idea was brought to my attention by his colleague, Dr. Kevin Folta in this blog post.

We can look forward to new, satisfying varieties that merge the best of production traits with the historical successes that delighted the senses. These are new heirlooms, and they open an exciting peek of what is coming in plant genetic improvement.

Here are more details of the story and the individual varieties! I hope you order some seeds and give your feedback to Dr. Klee so he can build your ideas into the future of tomatoes!

I often complained about the flavorless red things that you find in grocery stores, so here was a way to support researchers working to overcome that.

And Dr. Klee is not alone. Rutgers University went about restoring the old fresh market hybrid varieties that gave “Jersey Tomatoes” their deserved reputation.

Read about Ramapo, Moreton, and a processing tomato at the Rutgers site Rediscovering the Jersey Tomato .

And there are other research programs at Purdue, University of Michigan and Israel conducting similar efforts. No doubt there are others.

The future of good tasting grocery store, and fresh market tomatoes seems bright.

Building Healthy Soils in Vegetable Gardens: Cover Crops Have Got It Covered Part IV: Planting and Managing Cover Crops in Vegetable Gardens

Megan M. Gregory, Blog Contributor, Cover Crop Nerd, and Graduate Research Assistant, Cornell University
Email: meganmgregory1@gmail.com
Website: http://blogs.cornell.edu/gep/

This article is part of a four-part series about cover cropping in vegetable gardens. Stay tuned for Part III next week.

Once you’ve chosen cover crops that fit your vegetable rotation, management goals, and garden site (See Part III: Selecting Cover Crops for Vegetable Gardens), it’s time to plant! This article contains tips on sourcing seed, and planting and managing cover crops using hand tools.

Building Healthy Soils in Vegetable Gardens: Cover Crops Have Got It Covered Part III: Selecting Cover Crops for Vegetable Gardens

Megan M. Gregory, Blog Contributor, Cover Crop Nerd, and Graduate Research Assistant, Cornell University
Email: meganmgregory1@gmail.com
Website: http://blogs.cornell.edu/gep/

This article is part of a four-part series about cover cropping in vegetable gardens. Stay tuned for Part III next week.

As I outlined in Part I and II of this series, cover crops can serve many purposes in small-scale vegetable gardens, including soil quality improvement, nitrogen (N) fixation, weed suppression, and habitat for beneficial insects. To achieve maximum benefits from cover crops, it’s important to select appropriate species (or species mixtures) for each garden bed. In this article I’ll highlight promising annual cover crop species for different seasonal niches, management goals, and environmental conditions. Much of this information is based on preliminary results from two seasons of cover crop research in Brooklyn, NY community gardens.¹

Read more in Part III: Cover Crops III – Selecting Cover Crops

Building Healthy Soils in Vegetable Gardens: Cover Crops Have Got It Covered Part II: Types of Cover Crops – Non-legumes, Legumes, and Mixtures

Megan M. Gregory, Blog Contributor, Cover Crop Nerd, and Graduate Research Assistant, Cornell University
Email: meganmgregory1@gmail.com
Website: http://blogs.cornell.edu/gep/

This article is part of a four-part series about cover cropping in vegetable gardens. Stay tuned for Part III next week.

Vegetable gardeners are turning to cover crops to improve soil quality, add nitrogen (N) to the soil through legume N fixation, suppress weeds, and attract beneficial insects in their gardens. In this article I’ll introduce several groups of cover crops. Cover crop species can be broadly grouped into non-legumes (those that do not fix N, but take up and recycle nutrients left in the soil) and legumes (which fix N). Mixtures of non-legumes and legumes may offer the benefits of both types of cover crops.

Non-legume cover crops

Non-legume cover crops include species in several plant families:

Grasses (Poaceae) include oats (Fig. 1a), winter rye (Fig. 1b), sorghum-sudangrass, and Japanese millet.
Brassicas and mustards (Brassicaceae) include mustards, rapeseed, and tillage radishes.
Buckwheat (Fig. 1c, Polygonaceae) is a popular summer cover crop.

Fig. 1. Examples of non-legume cover crops used in vegetable gardens (Photo credits: M. Gregory)

*Fig. 1a. Oats* (Avena sativa) is a winter-kill cover crop in USDA Zones 7 and cooler. It is usually planted in late August, and dies with the first hard frosts.	*Fig. 1b. Winter rye* (Secale cereale) is a hardy over-wintering cover crop. It can be planted in September or October, and produces large amounts of biomass by May.	*Fig. 1 c.* Buckwheat (Fagopyrun esculentum) is a fast-growing summer cover crop, suitable for planting between spring and fall vegetable crops.

Benefits of non-legumes: ^{1, 2}

Prevent erosion – Non-legumes establish and grow quickly, provide rapid soil cover, and have dense, fibrous root systems that hold soil in place.
Build soil organic matter – Non-legumes produce large amounts of biomass, which contributes to soil organic matter.³
Retain and recycle nutrients – Non-legumes take up nutrients left in the soil after vegetable harvest, which prevents them from being leached out of the garden during heavy spring rains.
Suppress weeds – With their vigorous growth and high biomass, non-legumes can successfully compete with weeds, even in fertile soils. Some non-legumes (winter rye, sorghum-sudangrass, and Brassicas) also release chemicals that inhibit weed germination and growth. Residues of grass cover crops also provide a weed-suppressive mulch that lasts much of the growing season.
Disease management — Some Brassicaceae cover crops also release chemical compounds that may help control soil-borne pathogens and parasites(e.g., fungi, nematodes) upon incorporation. Winter rapeseed (Brassica napus) greatly reduced Rhizoctonia damage and Verticillium wilt in potato crops.^{1, 2}

Drawbacks and constraints of non-legumes:

Slow nutrient supply and/or N immobilization — Non-legumes have lots of carbon (C) relative to N during growth, which causes them to decompose slowly after mowing or incorporation. As a result, nutrients in non-legume residues may not be available to vegetable crops quickly. If non-legume residues are incorporated into the soil, they may actually immobilize (“tie up”) N for a few weeks as decomposer microbes take up soil N to balance the large amount of C in the plant residues they’re breaking down.¹ For this reason, it’s best to wait several weeks after incorporating a non-legume before planting vegetable crops.

Legume cover crops

Legume cover crops include field peas (Fig. 2a) crimson clover (Fig. 2b), hairy vetch (Fig. 2c), and cowpeas. They provide many of the same benefits of non-legumes, with the additional benefits of nitrogen fixation and feeding pollinators.

Fig. 2. Examples of legume cover crops used in vegetable gardens (Photo credits: M. Gregory)

*Fig. 2a.* Field peas (Pisum sativum) can be planted as a winter-kill or early spring cover crop. It should only be planted in full sun, as this legume performs poorly in shaded areas.⁴	Fig. 2b.Crimson clover (Trifolium incarnatum) over-winters in Zones 7 and up, and can be used as a summer or winter-kill cover crop in cooler zones. Crimson clover is a high biomass producer and is quite shade-tolerant.⁴	*Fig. 2c. Hairy vetch* (Vicia villosa) is the hardiest legume, and will over-winter in even the northernmost parts of the US. It is an excellent legume for adding fixed N to the soil.⁴

Additional Benefits of legumes:

Figure 3. A bumblebee visits a crimson clover flower in a community garden. Photo credit: M. Gregory.

Nitrogen fixation – Legume cover crops add ‘new’ nitrogen (N) to the soil through N fixation, which occurs when N-fixing bacteria in legume roots take N from the air and convert it to a form the plant can use. When legume residues break down, this N is added to the soil for food crops.⁵
Build soil organic matter and soil quality – While legumes don’t usually produce as much biomass as non-legumes, they also help build soil organic matter.^{6, 7} Legumes are also excellent soil conditioners, because legume roots ooze sugars that stick soil particles together in larger crumbs, or aggregates.^{8, 9} This helps the particles fit together loosely, making for a soft, porous soil.
Attract beneficial insects – Many legume species provide resources for beneficial insects. Crimson clover provides pollen and nectar for native pollinator bees (Fig. 3), and both crimson clover and hairy vetch host predators such as lady beetles, which eat many pest insects.¹

Drawbacks and constraints of legumes: ^{1, 3}

Slow growth, lower biomass — Legumes establish and grow more slowly than non-legumes, and usually produce lower biomass.
Less weed suppression — Legumes may not suppress weeds as effectively as non-legumes, particularly in soils with high N fertility. In Brooklyn gardens, legumes suppressed weeds in soils with low to moderate N fertility, but not in soils with high N fertility.⁴ Legume residues break down quickly, so weed control by legume mulch may be short-lived.
Seed cost — Legume seeds are more costly than non-legumes.

Cover crop mixtures

Mixtures of non-legumes and legumes often combine the benefits of both types of cover crops.

Benefits of nonlegume/legume mixtures:

Produce large biomass and suppress weeds effectively — In many cases, cover crop mixtures provide more complete soil cover, greater biomass production, and more effective weed suppression than plantings of just one species.^{1, 3} This is because mixtures of grasses and legumes use water, nutrients and sunlight very efficiently due to complementary root systems and growth habits. Grasses (like rye) also provide support for viny legumes (like hairy vetch), which allows the legume to access more light.
Increase N fixation — Planting legumes with grasses may enhance N fixation. Grasses out-compete legumes for soil N, forcing the legume to rely on N fixation. As long as the grass doesn’t suppress legume biomass (see below), this can increase the total amount of N fixed. Promising grass/legume mixtures for N fixation include rye/vetch and Japanese millet/cowpea.¹⁰
Optimize nutrient cycling and nutrient supply to crops — Mixtures provide the benefits of N ‘scavenging’ by non-legumes and N additions by legumes.¹ At maturity, grass-legume mixtures often have an ideal C:N ratio of 25:1 – 30:1, which promotes a steady release of N for vegetable crop use as the cover crop plants decompose. N-rich legume residues prevent N tie-up that can occur when incorporating pure grass residues, while C-rich grass residues slow the breakdown of legume residues such that N is released at a rate that vegetable crops can use through the growing season.^{2, 11}

Fig. 4. Examples of grass/legume mixtures used in vegetable gardens (Photo credits: M. Gregory)

*Fig. 4a.* Oats/ Field peas is a common winter-kill or early spring mixture. It should only be planted in full sun. Since oats may suppress field pea biomass and total N fixed,⁴ try seeding the field peas at a higher rate.	*Fig. 4b. Rye/ hairy vetch* is an excellent over-wintering mixture. The hairy vetch ‘climbs’ the rye, which allows the legume to access more light. In Brooklyn gardens, rye/vetch mixtures produced the highest biomass of any cover crop combination.⁴

Drawbacks and constraints of nonlegume/legume mixtures:

Reduced N fixation if nonlegume out-competes the legume – Mixing a non-legume with a legume may decrease the total amount of N fixed if the non-legume suppresses legume growth and biomass. This occurs in mixtures of: oats/field peas,^{4, 12} rye/crimson clover,⁴ and sorghum-sudangrass/cowpea.¹⁰ Seeding the legume at a higher rate may result in a more even distribution of nonlegume and legume biomass – gardeners can experiment to find the relative seeding rate that works best in your soil.

* * * * * * * * * * * * *

Understanding the benefits and limitations of non-legumes, legumes, and mixtures is a great starting point for selecting cover crops to plant in your garden. For guidance on choosing specific cover crops based on your vegetable crop rotation, management goals, and soil and light conditions, see Part III: Selecting Cover Crops for Vegetable Gardens.

References

(1) Clark, A. 2007. Managing cover crops profitably, 3rd ed. Sustainable Agriculture Network, Beltsville, MD. Accessed online at: http://www.sare.org/Learning-Center/Books/Managing-Cover-Crops-Profitably-3rd-Edition, 7 December 2014.

(2) Treadwell, D., N. Creamer, and K. Baldwin. 2010. An introduction to cover crop species in organic farming systems. Accessed online at: https://www.extension.org/pages/18542/an-introduction-to-cover-crop-species-for-organic-farming-systems, 7 December 2014.

(3) Snapp, S. S., S. M. Swinton, R. Labarta, D. Mutch, J. R. Black, R. Leep, J. Nyiraneza, and K. O’Neil. 2005. Evaluating cover crops for benefits, costs and performance within cropping system niches. Agronomy Journal 97(1):322-332.

(4) Gregory, M. M., L. E. Drinkwater. In preparation. Developing cover cropping practices to improve soil quality, nutrient cycling, and weed suppression in urban community gardens.

(5) Drinkwater, L. E. 2011. It’s elemental: How legumes bridge the nitrogen gap. The Natural Farmer, Summer 2011, pp. B-1 – B-6. Northeast Organic Farming Association, Barre, MA: Accessed online at: http://www.nofa.org/tnf/Summer2011B.pdf, 6 December 2014.

(6) Sainju, U. M., B. P. Singh, and W. F. Whitehead. 2002. Long-term effects of tillage, cover crops, and nitrogen fertilization on organic carbon and nitrogen concentrations in sandy loam soils in Georgia, USA. Soil & Tillage Research 63(3-4):167-179.

(7) Kong, A. Y. Y., J. Six, D. C. Bryant, R. F. Denison, and C. van Kessel. 2005. The relationship between carbon input, aggregation, and soil organic carbon stabilization in sustainable cropping systems. Soil Science Society of America Journal 69(4):1078-1085.

(8) Puget, P., L. E. Drinkwater. 2001. Short-term dynamics of root- and shoot-derived carbon from a leguminous green manure. Soil Science Society of America Journal 65(3):771-779.

(9) Haynes, R. J., M. H. Beare. 1997. Influence of six crop species on aggregate stability and some labile organic matter fractions. Soil Biology & Biochemistry 29(11-12):1647-1653.

(10) Drinkwater, L. E. 2011. A holistic view: Leguminous cover crop management in organic farming systems. The Natural Farmer, Summer 2011, pp. B-20 – B-24. Northeast Organic Farming Association: Barre, MA. Accessed online at: http://www.nofa.org/tnf/Summer2011B.pdf, 6 December 2014.

(11) Teasdale, J. R., A. A. Abdul-Baki. 1998. Comparison of mixtures vs. monocultures of cover crops for fresh-market tomato production with and without herbicide. HortScience 33(7):1163-1166.

(12) Schipanski, M. E., L. E. Drinkwater. 2012. Nitrogen fixation in annual and perennial legume-grass mixtures across a fertility gradient. Plant Soil 357(1-2):147-159.

Garden Site Selection

Shawn Banks: Extension Blog Contributor
Johnston County Extension Agent/Educator
North Carolina State University
shawn_banks@ncsu.edu

As an extension agent one question I often get asked by new gardeners is, “Where do I put a vegetable garden in my yard?” That leads to a lot more questions, but let’s answer the where question first. There are four basic considerations when selecting a garden site.

narrow strip of garden vegetables in a backyard area

The first thing to consider is the need for direct or full sunlight. Most vegetables need a minimum of six to eight hours in order to produce a crop. However, the more sunlight they get the more bounteous the harvest will be. If there isn’t a spot in the yard that receives full sun all day, then the question becomes, is it better to have shade in the morning or in the evening? Morning sun will dry the dew from the leaves, reducing the chance of fungal diseases infecting the leaves.

Speaking of dew, the next consideration is water. How close is the water source to the vegetable garden. Many vegetables need to have consistent moisture. That means a water source should be easy to access to keep the soil moist throughout the growing season. The further the water is from the garden, the less likely it is that the garden will get watered on a regular basis. Have you ever wondered why the tomatoes crack, or the radishes split? One of the most common reasons is that the soil was very dry and then it rained a lot and the plant was trying to store as much water as possible, causing the cracks and splits

Another consideration is airflow. Many foliar diseases are caused by fungal pathogens. Most fungi need water standing on the leaf for eight or more hours before they can infect the leaf. Good airflow will dry the leaves out before the fungi can infect the plant. A hedge, a solid fence, or even a house may obstruct airflow. Another way to obstruct airflow is to plant too close together, but that is a discussion for another time.

Lastly comes the phrase “out of sight, out of mind”. This is very true for a vegetable garden. When selecting where to place the garden, consider ease of access. Many people find that when the garden is way in the backyard, they don’t tend it often enough. The soil dries out. The weeds take over. The crops don’t get harvested in a timely manner. In short, the garden doesn’t succeed. Select a garden site that is close enough that you will see it and want to tend to it.

These four site characteristics are the most important when selecting the location for a vegetable garden. Remember, a vegetable garden site needs a minimum of eight hours of direct sunlight, consistent moisture, good airflow, and easy access. A site with all four of these characteristics will ultimately produce more, have fewer problems with fungal diseases, and be better taken care of because it is visited more frequently and loved.

Keep in mind that if you don’t have anywhere in your yard that works, many options, such as container gardens, can help you have a productive garden anywhere.

Garden Site Selection pdf

Building Healthy Soils in Vegetable Gardens: Cover Crops Have Got It Covered Part I: Introduction to Cover Cropping

Megan M. Gregory, Blog Contributor, Cover Crop Nerd, and Graduate Research Assistant, Cornell University
Email: meganmgregory1@gmail.com
Website: http://blogs.cornell.edu/gep/

This article is part of a four-part series about cover cropping in vegetable gardens. Stay tuned next week for Part II

What are cover crops, anyway?

Cover crops are close-growing plants sown in rotation with food crops, or inter-seeded between food crops to cover bare ground. They are not harvested, but rather are planted to improve soil quality and provide other benefits for crop production and the environment. Before planting the next vegetable crop, most cover crops need to be cut down. The shoots can be chopped (or mowed) and left as mulch on the soil surface, or incorporated into the soil.

There is a large body of research supporting the use of cover crops on organic and sustainable farms.¹ However, vegetable gardeners can successfully plant and manage cover crops with hand tools, and reap the benefits of this practice for their soil and crops.²

Why should I plant a crop that I’m not going to harvest?

Cover crops provide many benefits for future vegetable crop production, and for the garden agro-ecosystem as a whole. Incorporating cover crops in vegetable rotations may:

Increase soil organic matter levels, and therefore improve soil quality. As cover crop roots and shoots decompose, they build soil organic matter. This improves soil structure and water-holding capacity (Fig. 2), and increases slow-release nutrient reserves.³ Fresh cover crop residues also nourish beneficial soil fauna (bacteria, fungi, worms, etc.) that improve soil tilth and aeration, recycle plant and animal wastes, and release nutrients for crops to use.
Provide nitrogen for future food crops through legume nitrogen fixation. Cover crops in the legume family (e.g., beans, peas, clovers, and vetches) add “new” nitrogen (N) to the soil. Legumes host N-fixing bacteria in bumps on their roots, also called nodules (Fig. 3). These bacteria take N from the air and convert it to a form the legume can use . When the plant decomposes, the fixed N also becomes part of the soil organic matter. Eventually, this N is released by microbes for crop uptake.⁴
Improve nutrient retention and recycling. Over-wintering cover crops take up extra nutrients at the end of the growing season, which would otherwise be lost to leaching (when nutrients dissolve in rainwater and drain below the root zone, making the nutrients unavailable for plants). Over-wintering grasses like rye reduce N leaching by about 70% compared to bare soil.⁵
Suppress weeds. Growing cover crops reduce weed growth through competition (e.g., for space, light, moisture, and nutrients) and allelopathy (releasing chemicals that inhibit other plants). After , the cover crop mulch can prevent weed seedling emergence through the growing season.⁶
Attract beneficial insects. Cover crops often provide important resources (such as nectar and pollen and over-wintering habitat) for beneficial insects, including pollinator bees and natural enemies of insect pests like ladybugs and lacewing.¹
Increase or maintain crop yields with less inputs. Well-managed cover crops can improve vegetable crop yields, or reduce the amount of fertilizer needed to obtain good yields.^7-10

Figure 2. Demonstration illustrating the effect of soil organic matter (SOM) on water-holding capacity. Photo credit: Megan Gregory

On the left is soil from an urban garden that received a rye/vetch cover crop for more than five years, and therefore has high SOM.
On the right is soil from a garden that never received cover crops, and has lower SOM.
This photo was taken 30 minutes after pouring equal amounts of water through the soils. The high-OM soil held most of the water, while much water drained through the low-OM soil. Since both soils were of similar texture, the difference in water-holding capacity can be attributed to the SOM.

nodules on roots of cover crops — Figure 3. Nodules on the roots of legume cover crops: crimson clover (left) and hairy vetch (right). The nodules host nitrogen-fixing bacteria in the genus Rhizobia, which convert atmospheric nitrogen into plant-available forms. Photo credits: M. Gregory.

* * * * * * * * * * * * *

Vegetable gardeners have a number of cover crop options suited to different seasonal niches, management goals, and environmental conditions. To learn about the main groups of cover crops and how to select cover crops for your garden, see Part II (Types of Cover Crops) and Part III (Selecting Cover Crops).

References

(2) Gregory, M. M. and L. E. Drinkwater. In preparation. Developing cover cropping practices to improve soil quality, nutrient cycling, and weed suppression in urban community gardens.

(4) Drinkwater, L. E. 2011. It’s elemental: How legumes bridge the nitrogen gap. The Natural Farmer, Summer 2011, pp. B-1 – B-6. Northeast Organic Farming Association, Barre, MA. Accessed online at: http://www.nofa.org/tnf/Summer2011B.pdf, 6 December 2014.

(5) Tonitto, C., M. B. David, and L. E. Drinkwater. 2006. Replacing bare fallows with cover crops in fertilizer-intensive cropping systems: A meta-analysis of crop yield and N dynamics. Agriculture Ecosystems & Environment 112(1):58-72.

(6) Schonbeck, M. 2011. How cover crops suppress weeds. Accessed online at: https://www.extension.org/pages/18524/how-cover-crops-suppress-weeds, 6 December 2014.

(7) Abdul-Baki, A. A., J. R. Teasdale, R. Korcak, D. J. Chitwood, and R. N. Huettel. 1996. Fresh-market tomato production in a low-input alternative system using cover-crop mulch. HortScience 31(1):65-69.

(8) Abdul-Baki, A. A., J. R. Stommel, A. E. Watada, J. R. Teasdale, and R. D. Morse. 1996. Hairy vetch mulch favorably impacts yield of processing tomatoes. HortScience 31(3):338-340.

(9) Abdul-Baki, A. A., J. R. Teasdale, R. W. Goth, and K. G. Haynes. 2002. Marketable yields of fresh-market tomatoes grown in plastic and hairy vetch mulches. HortScience 37(6):878-881.

(10) Abdul-Baki, A. A., J. R. Teasdale. 1997. Snap bean production in conventional tillage and in no-till hairy vetch mulch. HortScience 32(7):1191-1193.

Pruning Overgrown Apple Trees

Ward Upham: Extension Blog Contributor
Extension Associate – Home Horticulture Rapid Response Coordinator
& Extension Master Gardener Coordinator
Kansas State University Extension
wupham@ksu.edu

Apple trees that are not pruned for several years will often produce so many branches that very little energy is left for fruit production. Overgrown apple trees are also difficult to harvest and spray. Gardeners who have such a tree are often at a loss as to how to get it back in shape.

Often the best (tongue-in-cheek) recommendation s for such a tree is to make one pruning cut at ground level and start over with a new tree. However, trees may have sentimental value that will make revitalization worth the time and effort. Realize that this will be a multi-year process because no more than 30 percent of the tree should be removed in one year. Here are some steps to follow:

Remove all dead wood. This does not count toward the 30 percent.
Remove suckers from the base of the tree.
Choose approximately six of the best branches to keep as scaffold branches. Remove all others. Branches should be cut flush to the branch collar. The collar is that natural swelling that occurs where a branch connects to the trunk or to a larger branch. Removing the collar would leave a larger wound that would take additional time to heal. Do not paint wounds. Research has shown that wounds heal more quickly if left open. Candidates for removal include branches with narrow crotch angles, which are more likely to break in wind and ice storms, and those that cross branches you will save. This may be all that is possible the first year if the 30 percent threshold has been reached.
Thin the branches on each scaffold branch. Remove crowded branches to open up the tree to light and allow humidity to escape. Shorten each scaffold branch by cutting back to a side branch. When you are through, the tree should have enough wood removed so that a softball can be thrown through the tree.

Severe pruning often will cause an apple to tree to produce vigorous side shoots from the trunk, called water sprouts. Main branches will also produce suckers that grow straight up. The suckers and water sprouts should be removed throughout the growing season so the center of the tree stays open.

In the case where a tree cannot be saved but you would like to preserve the apple tree variety, consider grafting. Scions taken from the old tree can be grafted onto a new rootstock to form a new tree. If you are not able to do so yourself, contact a local fruit tree nursery to find someone who may be able to help.

Pruning Overgrown Apple Trees pdf

Prepping Your Garden for The Next Growing Season

William H. McCaleb, Blog Contributor
Program Assistant for Agriculture and Natural Resources, Halifax County, VA. and Master Gardener

For gardeners in the eastern U.S., last year was a better than normal gardening season. Better than normal yield, better than normal precipitation, and in our case in Virginia cooler than normal which yielded excellent spring cool season crops as well as early summer crops.

But all good things must come to an end; that being the result of several heavy frosts. With that said, I am looking forward to next year’s challenges and what I want to grow for our family. Oh, for the taste of one more summer ripened tomato, but for now, that is a dream and it is time to reflect on what grew well in the garden as well as what didn’t do so well. Hopefully you have kept a garden journal to help you in this task. I find that writing down details of what is planted, the orientation, spacing, fertilization/liming rates and frequency, weekly rainfall amounts, production amounts, etc. is helpful as you start planning for the next season.

Like me, you should start thinking about what you want to grow in 2015. Take time to reflect on your 2014 garden production, care, and location. Also, evaluate what went right and what went wrong with the plants and varieties you planted and harvested. This will start you off in the right frame of mind in preparing for the next growing season. Good planning and preparation for next year gives you the tools to have an even better gardening season. A successful vegetable gardener is a happy well fed gardener!

I know, you too are already missing those fresh tomatoes, potatoes, peppers, squash, okra, and other great home grown vegetables we treated ourselves to this year, but the next season is ‘just around the corner’ so to speak. After all the days are getting a little longer. Spring can’t be far away!

If you just happen to live in an area that hasn’t had frost yet, take your prompt from your plants: when annuals and seasonal vegetables turn brown and begin to die back, it is time to clean up your garden.

Clean up the Garden
Your best action is to remove any spent or failing plant materials. Experienced gardeners know that many of the bacteria, fungi, and other disease-causing organisms that caused those diseases. Pathogens that are sources of those diseased plants this past season can survive over the winter in dead leaves, stems, roots, and dropped fruits that get left in the garden. Much like a piece of bread that is kept too long and looks like it has penicillin growing on it, garden debris also will carry the pathogens that can come alive with those same problems when the temperatures begin to rise in the spring. Prevention of diseases and insect infestation now, will keep you from a repeat of problems in next year’s garden.

A good leaf rake, given enough ‘elbow grease’, works well in getting the bulk of dead plant material out of your garden. If you experienced early or late blight or other tomato related diseases this past growing season, you want to make sure you reduce, to the best of your ability, the risk of repeating that problem again next year. Yes, there are many new varieties of vegetables available today that are ‘resistant’ to some of these diseases, but ‘resistant’ does not mean they are immune to them. You don’t want to take the chance of returning pathogens, so do a good job, cleaning and ‘sanitizing’ your garden now. Make sure, when removing the plant debris, that you totally destroy that debris so that no pathogens are left behind.

To Compost or Not!
Can you compost this dead plant material and use it next spring? Information that you find from Extension offices across the U.S. will recommend that you do not. The reason being is that most people do passive composting i.e. put it in a pile, and then using what compost develops, put the compost back in the garden for the next season. It is best to burn the plant material; this will destroy the pathogens and weed seeds as well and return some carbon back into the ground when you spread it out. Please check local/state laws prior to burning. Many states and/or localities have burn bans especially this time of the year. Another method, if your local law allows it you can bag the material and send it to the landfill. Each year there are more localities that ban yard waste from their landfills. If you are not sure, check with your locality to learn more about your local waste and recycling laws.

If you do decide to go with active composting; composting at a temperature 140°F, or higher, will destroy many of the disease organisms as well as many weed seeds. You will need a temperature probe to monitor compost temperatures. It’s really not hard to source a compost thermometer either through the internet or local retail outlets such as garden centers or nursery supply stores. If in doubt about your compost pile reaching these high temperatures, it is best to side with caution and discard the material by properly bagging it or by burning based on your local ordinances.

Preventing Overwintering Pathogens
Some of our most notorious insects of the garden such as Mexican bean beetle, squash vine borers, European corn borer, cabbage loopers, can also overwinter in garden debris. Larvae will use debris as a safe harbor. Flea beetles and spider mites, as well, can find food and winter shelter in spent plant material and weeds.

After you have finished cleaning up the debris from your garden, it is time to turn over the soil to both aerate and break up any remaining debris into smaller pieces that will be turned under. A good rototiller will help make this job easier. Once buried, any plant material left will decompose more rapidly.

For some pests and pathogens, turning over the soil after removing spent plant materials is recommended as the main line of defense against overpopulation next year. Consider this information from “Home and Horticultural Pests: Squash Bugs and Squash Vine Borers,” from Kansas State University,

“A vigorous autumn… rototilling can physically destroy cocoons and larvae (of the squash vine borer). Brought to the surface, cocoons and larvae are more susceptible to predation by birds and exposed to cold winter elements, leading to their demise. Deep plowing physically destroys cocoons and larvae burying them deep beneath the soil surface so pupated moths become entombed underground.”

Steps to a Healthier Garden
If you haven’t done a soil test in three years or more, it is time to retest and determine the needs of your garden soils based on what you will be growing in the next season. Soil test kits and instructions are available from your local Extension Office. Also, in planning next year’s garden, rotation of your crops is a must do item. This simple action will help keep disease issues down. If your soil test(s) recommend liming, you can go ahead and put down lime this time of year, allowing it to start adjusting the pH. If the ground is frozen already, wait until spring. As you add lime, you can also help build soil structure by incorporating compost or shredded leaves. These soil additives will also add beneficial micro-nutrients and beneficial organisms. If you want to further build the soil, you may want to consider putting in a cover crop that will not only hold soil, but when tilled in early spring, will further build a healthier garden soil. A legume such as white or red clover would be something to consider. Check with your local Extension Office for best cover crop recommendations for your area.

Prepping Your Garden for the Next Growing Season (pdf)

References:

http://pubs.ext.vt.edu/426/426-334/426-334.html
http://www.ksre.ksu.edu/bookstore/pubs/mf2508.pdf

image sisters — “Three Sister’s Garden-Fall Clean-up “Southern Virginia Botanical Gardens” Photo by W. McCaleb 10/28/14 Corn, Beans, and Squash was grown here as the native Cherokee have done for centuries. Cleaned up and ready for spring 2015!