Posts Tagged ‘18:17’

WCU Volume 18, Issue 17 – July 9, 2010

Friday, July 9th, 2010

PDF Version of WCU 18:17 – July 9, 2010

In this issue:

Vegetables
Vegetable Crop Insects
Cucurbit Downy Mildew Found in Delaware
Any Hope for Pickling Cucumbers with Resistance to Cucurbit Downy Mildew?
Balancing Growth and Fruiting
Potato Disease Advisory #14 – July 8, 2010
Problems with the Hot, Dry Weather
Viruses and Other Problems Found in Watermelon and Cantaloupe in Central Maryland

Agronomic Crops
Agronomic Crop Insects
Bacterial Stalk Rot in Corn
Will Roundup Ready® Alfalfa Be Back?
Grain Marketing Highlights

Announcements
Sustainable Vegetable Production Demonstration – July 14
Rutgers University Hybrid Hazelnut Field Day – July 31
Soybean Cyst Nematode Workshop – August 3

Weather

Rutgers University Hybrid Hazelnut Field Day

Friday, July 9th, 2010

Saturday July 31, 2010     8:30 a.m. – 3:00 p.m.
Rutgers: NJ Agricultural Experiment Station
59 Dudley Rd.
Cook Campus, Multipurpose Room A
New Brunswick, NJ 08901-8520

Join Dr. Tom Molnar and his hazelnut research colleagues to learn about hybrid hazelnuts and the Rutgers University hazelnut breeding and research program at the 2010 Rutgers Hazelnut Field Day. The field day will include an overview of hazelnuts at Rutgers and presentations on the Arbor Day Foundations’s hazelnut research program and the Hybrid Hazelnut Consortium, the Ferrero Candy Company in Italy, and experiences of local hazelnut growers assisting in research projects.  Lunch and an afternoon tour of the hazelnut research fields are included.

Cost of the field day is $20. To register and for more information go to: http://rutgershazelnutday.eventbrite.com/

Sustainable Vegetable Production Demonstration

Friday, July 9th, 2010

Wednesday, July 14, 2010     6:00 – 8:00 p.m.
St. Joseph’s Center Bountiful Harvest Garden
355 W. Duck Creek Rd, Clayton, DE  19938

This small plot has big impact and highlights important sustainable growing techniques.  This workshop will highlight sustainable vegetable production practices including various mulching techniques, reduced tillage and integrated pest management.

This meeting is free and everyone interested in attending is welcome.

To register, request more information or if you require special needs assistance for this meeting, please call our office in advance at (302) 831-2506. Please preregister by July 12.

See you there!  
Anna Stoops, NCC Extension, Agricultural Extension Agent

Will Roundup Ready® Alfalfa Be Back?

Friday, July 9th, 2010

It appears that with a Supreme Court ruling a few weeks ago that Roundup Ready® alfalfa will eventually be available for planting. The questions that remain include not only when will this occur but what restrictions will be imposed on planting the crop and in what sections of the country it will be allowed. If you haven’t had a chance to read some of the articles that expound on the Supreme Court’s ruling, please take the time to look them up and read them over. It seems that both sides are able to claim victory from the ruling so it probably means that there will still be a number of months ahead of us before final rules are set in place so that in some areas and under some conditions, we can return to using this new technology. Monsanto has stated that they believe that plantings will be possible this fall while others doubt that this timeline can be achieved. If you’re interested in the technology and for growers who like to grow pure alfalfa hay or who like the ease of a single herbicide for most weed control, keep in touch with the latest developments in this story to know when it will be permissible to plant Roundup Ready alfalfa again.

Grain Marketing Highlights

Friday, July 9th, 2010

Carl German, Extension Crops Marketing Specialist; clgerman@udel.edu

Pre-Report Analysis (7-8-10)

Markets Explode to Upside Ahead of USDA Report
The Dow Jones Industrial Average closed 274.66 points higher Wednesday at 10,018.28. The overnight session saw the Dow Jones futures trade 17 points lower, indicating the market could see light selling interest early Thursday. The overnight crude oil market was $.75 higher at $74.82. Brent crude was $.72 higher at $74.23. The U.S. dollar index is 0.118 higher at 83.940.

Heading into Friday’s USDA July Supply and Demand report the looming question remains: How much will U.S. corn ending stocks be cut for both the ‘09/‘10 and ‘10/‘11 marketing years? Further, if last week’s Quarterly Stocks report is accurate, then U.S. soybean stocks could drop to 100 million bushels for the ‘09/‘10 marketing year. The net impact of lowering ending stocks for U.S. soybeans will be offset to some degree by expectations for large world ending stocks of soybeans. The wheat market continues to be buoyed by weakness in the dollar. However, trade expectations are for all U.S. wheat stocks to exceed 1 billion bushels in tomorrow’s report.

Corn
Commercial buying continues to provide support, though Wednesday’s trade was dominated by noncommercial buying tied to the almost 300-point rally in the DJIA. Also impacting the corn market, to a lesser extent at this point in time, is the Weekly Crop Conditions report that had the overall rating for the nation’s corn crop declining by a couple of points for the third week in a row, now placed at 71 percent good to excellent as compared to 73 percent a week ago and tied with the year ago rating. If one dig’s a little deeper and considers only the five largest corn producing states: Iowa, Illinois, Indiana, Nebraska, and Minnesota this week’s ratings are noted to be below the national average for Iowa (65), Illinois (68), and Indiana (62), the three largest corn producing states, while Nebraska (83) and Minnesota (89) ratings are above the national average.

Pre-report estimates had weekly corn export sales at 33.5 to 57.1 million bushels. The weekly report showed total export sales of 28.3 million bushels, with old-crop sales of 25.6 million bushels, well above the 5.8 million bushels needed this week to stay on pace with USDA’s demand projection of 1.95 billion bushels. Total shipments of 37.5 million bushels were below the 47.9 million bushels needed this week. This report should be considered neutral to bearish.

Soybeans
Soybean contracts posted impressive 30-cent-plus gains Wednesday due in large part to spillover buying from the DJIA and other commodities. The weekly crop conditions report showed a decline of one percentage point for the U.S. soybean crop, now placed at 66 percent good to excellent. Some follow-through action may be seen Thursday, though the market could also begin to die down in front of Friday’s USDA reports. Pre-report estimates are indicating these numbers to be neutral to bullish, with the most bearish world production numbers already built into the market. The weekly report showed total export sales of 26.3 million bushels, with old-crop sales of 9.7 million bushels above the 1.3 million bushels needed to stay on pace with USDA’s demand projection of 1.455 billion bushels. Total shipments of 5.1 million bushels were below the 10 million bushels needed this week. This report should be viewed as neutral to bullish.

Wheat
Despite pre-report estimates that have new-crop wheat ending stocks (domestic) coming in over 1 billion bushels in Friday’s USDA Supply and Demand and Crop Production reports, the wheat market has been able to continue its strong rally. Support has come from the sharp sell-off in the U.S. dollar index, in addition to noncommercial short-covering that has been noted in the Chicago market.

Market Strategy
Last week’s Quarterly Stocks and Planted Acreage reports gave commodity traders their first indication that U.S. corn and soybean stocks may not grow this year and/or might not be as large as estimated in the June report. Tomorrow’s report will shed some light on the subject, although one needs to bear in mind that the June 30 planted acreage report was not survey based for corn and soybeans and will not become certifiable until the latter part of August. Currently, Dec ‘10 corn futures are trading at $3.95; Nov ‘10 soybean futures at $9.40; and July SRW wheat futures are trading at $5.15 per bushel.

July Supply and Demand USDA Report Highlights (7-9-10)

There will be less corn and more wheat on hand in the U.S. at the end of both the current and new crop years, according to USDA’s July supply and demand report released early this morning. U.S. corn ending stocks for both 2009-10 and 2010-11 were lower than what was estimated in June, but were above the average pre-report estimates. Soybean ending stocks were also reduced from the June estimate while wheat ending stocks were increased. In its monthly crop production report, the department raised its estimate of this year’s wheat crop by 149 million bushels, a little bigger increase than many analysts had forecast, so it may be bearish for the wheat market.

U.S. SUPPLY AND DEMAND CHANGES
USDA took old crop (‘09/‘10) corn stocks down to 1.478 billion bushels, reflecting a 175 million bushel increase in feed and residual use and a 50 million bushel cut in corn for ethanol. This change was expected, following the June 30 Quarterly Stocks report, which was below trade expectations and implied larger-than-expected consumption.

For new crop (‘10/‘11) corn, USDA left yield unchanged at 163.5 bushels per acre and cut planted and harvested acreage to match the June 30 acreage report (planted acreage, 87.9 million acres, harvested 81 million acres), resulting in a production estimate of 13.245 billion bushels. Incorporating the decrease in old-crop ending stocks and a 50 million bushel cut in ‘10/‘11 marketing year exports, ending stock estimates for the ‘10/‘11 marketing year are now projected at 1.373 billion bushels. The projected average farm price was increased by 15 cents per bushel on both ends of the price range, now estimated at $3.45 to $.4.05 per bushel.

For soybeans, USDA pegged old crop ending stocks at 175 million bushels, down 10 million bushel from last month, reflecting a 5-million-bushel increase in both crush and exports. Prior to the report, some analysts were suggesting old crop soybean stocks could eventually decline to 100 million bushels.

New crop soybean acreage was adjusted to match the June 30 acreage report (78.9 million acres planted, 78.0 million acres harvested) and yields were left unchanged from June’s 42.9 bushels per acre, with production now projected at 3.345 billion bushels, up 35 million bushels from June’s report. New crop ending stocks remain at 360 million bushels, as the increase in production was offset by the decrease in beginning stocks and a 5 million bushel increase in crush and a 20 million bushel increase in exports. USDA’s projected season average farm price was raised a dime on both ends of the price range, now estimated at $8.10 to $9.60 per bushel.

Old crop wheat ending stocks were forecast at 973 million bushels, up from 930 million bushels in June, as exports were lowered 20 million bushels, and there were also cuts in seed and feed and residual use. New crop wheat ending stocks were forecast to total 1.093 billion bushels, the result of the increase in production, carry-in stocks, lower feed and residual use. Exports were projected to be 100 million bushels higher. USDA’s projected season average farm price was raised 20 cents per bushel on both ends of the price range, now estimated at $4.20 to $5.00 per bushel.

This year’s all wheat crop will total 2.216 billion bushels, up from the June forecast of 2.067 b bu. U.S. all-wheat yield is forecast at 46.9 bushels per acre, up 0.3 bushels from last month and up 2.7 bushels from last year, and the third highest yield on record. The harvested area for all wheat was reported to be 32.1 million acres in the June 30th Acreage report.

WORLD Supply and Demand
Old crop world corn stocks are forecast at 139.59 million metric tons, down from 143.41 MMT in June. For new crop, world corn stocks were lowered 6.24 MMT, from 147.32 MMT forecast in June, with nearly half the decline driven by reductions in carry-in and production in the U.S. World ending stocks are viewed as bullish for corn with a decrease seen in both ‘09-‘10 and ‘10-‘11 marketing years.

Old crop world soybean stocks are forecast at 65.35 million metric tons, down from 65.47 MMT in June. For new crop, world soybean stocks were raised 0.77 MMT, from 66.99 MMT forecast in June. Soybean ending stocks are bearish with both old crop and new crop (‘09-‘10 and ‘10-‘11 marketing years) resulting in ending stocks-to-use ratios of greater than 27 percent.

Old crop world wheat stocks are forecast at 193.02 million metric tons, up from 192.90 MMT in June. For new crop, world wheat stocks were lowered 6.88 MMT, from 193.93 MMT forecast in June, as world production was projected 7.5 million tons lower. World wheat ending stocks should be viewed as bearish with ‘10-‘11 ending stocks-to-use at 28 percent.

U.S. ENDING STOCKS (Million Bushels) 2009-2010

  July Avg High Low June 2008-09
Corn 1,478 1,404 1,600 1,214 1,603 1,673
Soybeans 175 171 195 138 185 138
Grain sorghum 28 29 36 25 33 55
Wheat 973 968 973 940 930 657

U.S. ENDING STOCKS (Million Bushels) 2010-11

  July Avg High Low June
Corn 1,373 1,337 1,734 833 1,573
Soybeans 360 354 387 250 360
Grain sorghum 33 32 39 25 38
Wheat 1,093 1,033 1,104 852 991

WHEAT PRODUCTION (Million Bushels) 2010-2011

  July Avg High Low June 2009-10
All Wheat 2,216 2,164 2,209 2,106 2,067 2,216
All Winter Wheat 1,505 1,494 1,525 1,472 1,482 1,523
HRW 1,011 996 1,020 973 979 919
SRW 268 279 284 270 284 404
White 226 220 224 210 219 200
Spring 607 576 614 514 584
Durum 104 102 115 91 109

WORLD ENDING STOCKS (Million metric tons)

  2010-2011 2009-2010
  July June July June
Wheat 187.05 193.93 193.02 192.90
Corn 141.08 147.32 139.59 143.41
Soybeans 67.76 66.99 65.35 65.47

WORLD PRODUCTION (Million Metric Tons)

  2010-2011 2009-2010
  July June July June
Brazil soybeans 65.0 65.0 69.0 69.0
Argentine soybeans 50.0 50.0 54.5 54.0
Brazil corn 51.0 51.0 53.0 53.0
Argentina corn 21.0 21.0 22.5 22.5
Australia wheat 22.0 22.0 22.5 22.5
Canada wheat 20.5 24.5 26.5 26.5

For Supply and Demand Estimates (WASDE): http://usda.mannlib.cornell.edu/
For Crop Production: http://usda.mannlib.cornell.edu/

Bacterial Stalk Rot in Corn

Friday, July 9th, 2010

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

If you are irrigating from surface water sources such as ponds or ditches, there is a risk of bacterial stalk rot. The bacteria are in the irrigation water and if the whorl or the ear leaf sheath and ear shank provide a place for water to sit, bacteria can enter the stalks and cause a soft decay of leaf sheath stalk and ear shanks. It is foul smelling as well. It appears as random infected plants in the field. Corn is thought to be susceptible for a short period of time and the older the corn the less likely infection will occur. There is no chemical control for bacterial stalk rot. Treating irrigation water in the system with hypochlorite is an alternative.


Bacterial stalk rot

Agronomic Crop Insects – July 9, 2010

Friday, July 9th, 2010

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

Alfalfa
If you have not been scouting fields, be sure to keep a close watch for leafhoppers. Remember, the nymphs can quickly cause damage and once yellowing is present significant damage has already occurred both in season as well as to the long term health of the stand. With the hot, dry weather, you should consider reducing treatment thresholds by at least one-third.

Field Corn
We are starting to see an increase in Japanese beetles and corn rootworm beetles feeding on corn silks. Both of these insects can potentially interfere with pollination. However, silk feeding by these beetles will not reduce pollination if they cut the corn silks after pollination has already taken place. As a general guideline, an insecticide treatment may be needed if two or more Japanese beetles or corn rootworm beetles are present per ear and silks are clipped to less than ½ inch prior to pollen shed.

Soybeans
We continue to see a wide variety of defoliators present in fields including Japanese beetles, green cloverworm, grasshoppers, painted lady caterpillars, blister beetles and silver spotted skipper. The best way to make a treatment decision in full season soybeans is to estimate defoliation. Before bloom, the defoliation threshold is 30%. As full season beans enter the reproductive stages, the threshold drops to 15% defoliation. Remember that double crop soybeans can not tolerate as much defoliation as full season beans so be sure to watch newly emerged fields carefully.

We continue to find economic levels spider mites in full season and double crop soybeans. With the current hot, dry weather, populations are often found field wide so be sure to scout the entire field because edge treatments may not be effective.

We have also found our first soybean aphids in a full season soybean field in New Castle County. Remember that this aphid is favored by cooler temperatures. The treatment threshold established in the Midwest is 250 aphids per plant from R1 through R5 stage of growth. The following links from the University of Wisconsin provides good information in sampling, stages of soybean growth and development, thresholds and treatment guidelines (http://www.plantpath.wisc.edu/soyhealth/aglycine.htm)
(http://www.plantpath.wisc.edu/soyhealth/pdf/aphid_thresholds.pdf)

Viruses and Other Problems Found in Watermelon and Cantaloupe in Central Maryland

Friday, July 9th, 2010

Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu

Cucumber mosaic virus (CMV) has been found in some watermelon fields in central Maryland. CMV is not uncommon in the NE United States, but in a two-year survey of pumpkin that Kate Everts, Karen Rane, Mark VanGessel and I did in Maryland and Delaware we did not detect CMV in any pumpkin field we sampled. CMV is transmitted primarily by aphids, but also by cucumber beetles, mechanically and to a lesser extent in seed. Many species of aphid can vector the virus in a non-persistent manner – the most common species in Maryland are: Melon aphid Aphis gossypii and Green peach aphid Myzus persicae. The virus is acquired by aphids within 10 seconds after they begin to probe an infected plant. The virus can be transmitted to other plants by aphids in less than one minute. This is why insecticides do not stop initial infections. Aphids lose the ability to transmit CMV after about 2 minutes and completely lose the ability after 2 hours. There are many strains or types of CMV, some isolates can lose their transmissibility by one aphid species but retain their transmissibility with another. In one field I visited there were many early season striped cucumber beetles and I think they may have been responsible for transmitting the virus from weeds to the watermelon in this field. The virus symptoms were first seen a few weeks ago – very early in the season for us to be seeing virus symptoms in watermelon fields. Some of this may be due to early season cucumber beetles transmitting the virus and some may be due to the extreme heat and drought we are experiencing. The drought is causing weeds to wither and the aphids that are present on them are moving earlier than they normally would to greener fields—like our well cared-for cucurbit fields.

The symptoms I have seen on watermelon are rather non-descript (Fig. 1) and look like they could be due to many things, including herbicide injury. Leaves of new growth are crinkled and deformed with a slight yellowing to them. CMV produces a systemic infection in most host plants with the older plant tissues that developed before infection rarely being affected by the virus. Tissues that develop after infection are affected to varying degrees. The concentration of the virus increases for several days following inoculation, and then decreases until it levels off. While there is transmission through seed in 20 host species, the most important source of virus may be weeds, which allow for overwintering of the virus. In addition to seeds, CMV overwinters in many perennial weeds and some crop plants. The perennial weeds wild ground cherry, horse nettle, milkweed, ragweed, pokeweed, nightshade, and various mints can harbor the virus in their roots, and in the spring the virus migrates to new growth, which aphids then transmit to susceptible crop plants. CMV is easily transferable through sap carried on the hands, clothes and tools of people harvesting fruit, weeding or turning vines in a watermelon field.

Figure 1. New growth on watermelon with CMV symptoms

There are some CMV resistant (tolerant) cucumber varieties available that produce a good crop, but most other cucurbits are susceptible to CMV. Using reflective mulch reduces the early season infection from aphids and gives an additional 2-4 weeks of a virus-free cucurbit field. Once the plants cover the plastic the reflective mulch ceases to be an effective deterrent. Pesticides only work to reduce the in-field spread of aphids and therefore, CMV and other viruses.

I have also seen virus symptoms in cantaloupe recently. Leaves are mottled and puckered (Fig. 2), and symptomatic tissue tested positive in a generic potyvirus test. Initial tests for the common potyviruses Watermelon Mosaic Virus, Zucchini Yellow Mosaic Virus and Papaya Ringspot Virus were negative for these cantaloupe leaves. Additional tests are being performed to try to identify which specific potyvirus is affecting the cantaloupe.

Figure 2. Cantaloupe with potyvirus symptoms

In addition to the virus problems, I have seen, especially in the last two weeks, a great increase of necrotic spot appearing on the crown leaves of watermelon plants (Fig. 3). This is being caused by a combination of air pollution problems-hot humid air not moving much and the fact that the plant takes nutrients from the crown leaves when there is a heavy demand from the growing fruit. This results in the crown leaves turning brown and eventually breaking down. In cantaloupe I have seen some leaf marginal chlorosis (yellowing of leaf margins) of some leaves (Fig. 4). This is often caused by salt deposits (from foliar nutrient or pesticide sprays) that accumulate around leaf margins, which have a toxic effect on the gas exchange pores (hydathodes) located at leaf tips. This is commonly seen under high temperature and humidity.

Figure 3. Necrotic spots on watermelon crown leaf

Figure 4. Marginal chlorosis of cantaloupe leaf

Problems With the Hot, Dry Weather

Friday, July 9th, 2010

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

The excessively hot and dry weather is taking its toll on dryland field crops. While most vegetables are irrigated, we are still seeing heat and drought related problems. Some common problems are:

Sunscald
Sunscald is evident on many vegetables. This is especially the case where irrigation has not been able to keep up and plants have wilted for a period of time, exposing fruits. Dark colored fruits are most susceptible. Sunscald is most common on peppers, tomatoes, and cucumbers but also can be seen on watermelons, melons, and some squash. Exposed potato tubers are also susceptible. Sunscald is controlled by not allowing plants to wilt and having adequate leaf cover.

Blossom End Rot
Blossom end rot on peppers and tomatoes is common at this time due to the inability of plants to move enough calcium into expanding fruits, especially if plants are water stressed for periods of time. Blossom end rot increases in excessively hot weather. Blossom end rot can be reduced by addition of soluble calcium containing fertilizers and by irrigating so that plant demands are being met.

Leaf Curl
Plants such as tomatoes, peppers, and potatoes often react to hot weather by having increased amount of permanent leaf curling. No control measures are necessary.

Leaf Scorch
Leafy vegetables under heat and water stress often will have leaf edges that scorch. This also can be compounded by calcium deficiencies or reduction in calcium movement to the edges of rapidly expanding leaves. Many other vegetables will show leaf scorch symptoms. Having adequate irrigation management is critical to avoiding leaf scorch. Evaporative cooling from overhead irrigation can also help reduce leaf scorch.

Transplant Collapse
Late transplanted vegetables on black plastic mulch can collapse due to heat necrosis of stems touching the plastic mulch or by overheating of beds under the plastic so that roots are killed. Control by using white plastic mulch instead of black, using a larger planting hole to dissipate the excess heat, running overhead irrigation to cool the mulch, and keeping beds moist with drip irrigation.

Balancing Growth and Fruiting

Friday, July 9th, 2010

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

As fruiting vegetables reach full size, we often get called to look at problems with fruit set. Poor fruit set, blossom drop, and fruit abortion can be caused by many factors including heat stress, water stress, insect and mite damage, chemical injury, lack of pollinating insects, and nutrient deficiencies to name few. Excessive vegetative growth is another common reason for poor fruit set or delayed fruit set.

Excessive vegetative growth commonly occurs when plants are grown under high fertility conditions and are being heavily watered. Under these conditions, flowering and fruiting is delayed as plants continue to put on new growth. High plant populations or close plant spacing can further compound the problem.

In this vegetative growth mode, the hormone balance is such that flowering and fruiting is limited. This will not change until growth slows and the hormone balance shifts, signaling flowering.

In addition, as the area covered by leaves and stems increases, so does shading within crop canopies. New growth starts to shade out older growth. Unfortunately, the stem nodes where flowering and fruiting is occurring is often so shaded that nearby leaves cannot produce enough photosynthate to support these flowers and fruits.

Heavy dense canopies can also reduce the effectiveness of pollinating insects as flowers are more difficult to access.

Another problem with excessive vegetative growth is creating a high humidity environment in the canopy that favors plant diseases. Sclerotinia (white mold), Phytophthora, Pythium, Septoria, and Botrytis are examples of diseases that can become problems in dense canopies. Often, these diseases will infect flowers and young fruit, causing them to drop.

We commonly see delayed fruiting, poor fruit quality, and reduced fruiting in vine crops with excessive growth. This includes watermelons, cantaloupes, and pumpkins. This is especially true of robust vining varieties. In contrast, bush and semi-bush forms of cucurbits such as some summer squashes and winter squashes have fewer problems with overgrowth. Tomatoes are also susceptible to excessive plant growth, reducing fruit set and quality. Snap beans and lima beans with excessive foliage are at high risk for diseases infecting pods, causing pod drop. Cucumbers with excessive foliage also are high risk for fruit diseases.

The goal in producing these fruiting vegetables is to balance vegetative and reproductive growth. This is done by managing fertility, especially nitrogen (N), to have enough nutrients available to grow a healthy plant but not to promote excessive growth. Nitrogen fertilization rates in the commercial vegetable production recommendations guide for Delaware should be consulted. In addition, nitrogen release from manures or other organic sources needs to be considered in overall N applications. We often see over-fertilization problems in fields with a history of heavy manure use or with high organic matter where N is being released from these sources as they mineralize.

Water should be managed so that plants are not over-irrigated. You certainly should not let plants become so water stressed that growth is affected. However, low levels of water stress actually can promote reproductive development in many vegetables.

Crop type, plant type, and plant morphology should also be considered prior to planting. Varieties that produce heavy growth (long vines or stems, many branches, large leaves, etc.) need to be spaced further apart to avoid overcrowding. Some vigorous varieties will even require reduction in fertilizer to control growth. Also consider how each crop responds to high fertility and heavy irrigation. Crops such as sweet corn, summer squash, and peppers normally do not have problems with excessive growth and will yield well under those conditions. In contrast, tomatoes, watermelons, cantaloupes, and lima beans will have yield reductions if fertility and irrigation are not managed well.