Posts Tagged ‘20:8’

WCU Volume 20, Issue 8 – May 11, 2012

Friday, May 11th, 2012

PDF Version of WCU 20:8 – May 11, 2012

In this issue:

Vegetable Crops
Vegetable Crop Insects
Potato Disease Advisory #1 – May 10, 2012
Cucurbit Downy Mildew Fungicide Decisions
MELCAST for Watermelons
Transplant Shock
Bulb Mite Found in Problem Garlic Fields
Garlic Bloat Nematode found in Several Garlic Samples

Agronomic Crops
Agronomic Crop Insects
Soybean Rust Risk Assessment
Small Grain Disease Updates
Grain Marketing Highlights

Announcements
University of Delaware Small Fruit Twilight – May 22

Weather

Grain Marketing Highlights – May 11, 2012

Friday, May 11th, 2012

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

U.S. Supply/Demand Summary

U.S. Highlights

•U.S. ending stocks of corn were increased 50 million bushels from the April estimate due to lower feed usage. The increase was not expected.

•Corn ending stocks for the ‘12/’13 marketing year were estimated at 1.881 billion bushels, nearly 180 million bushels above average pre-report expectations.

•As a result ending stocks-to-use for the ‘12/’13 marketing year are expected to increase to 13.7%, more than double the 6.7% for the current marketing year.

•U.S. soybean ending stock estimates for the current marketing year were lowered 40 million bushels sending the stocks-to-use estimate lower, now estimated at 6.8%.

•U.S. soybean ending stocks for the next marketing year are projected at 4.4%, a record tight level.

•Wheat ending stocks were reduced 25 million bushels due to an increase in exports.

•The domestic stocks-to-use ratio for all wheat was reduced from 36.2% to 34.7% for the ‘11/‘12 marketing year.

US Supply/Demand Estimates, May 10, 2012, Million Bushels

Corn Soybeans Wheat
Crop Year 11-12 11-12 12-13 11-12 11-12 12-13 11-12 11-12 12-13
Report Date 10-Apr 10-May 10-May 10-Apr 10-May 10-May 10-Apr 10-May 10-May
Carryin 1,128 1,128 851 215 215 210 862 862 768
Production 12,358 12,358 14,790 3,056 3,056 3,205 1,999 1,999 2,245
Imports 20 20 15 15 15 15 120 120 120
Total Supply 13,506 13,506 15,656 3,286 3,286 3,430 2,982 2,982 3,133
Feed 4,600 4,550 5,450 180 180 230
Crush/Mill* 1,375 1,375 1,395 1,630 1,645 1,655 930 930 945
Ethanol Prod. 5,000 5,000 5,000
Seed/Other 30 30 30 116 116 125 79 79 73
Exports 1,700 1,700 1,900 1,290 1,315 1,505 1,000 1,025 1,150
Total Use 12,705 12,655 13,775 3,036 3,076 3,285 2,189 2,214 2,398
Carryout 801 851 1,881 250 210 145 793 768 735
Stocks/Use Rat 6.3% 6.7% 13.7% 8.2% 6.8% 4.4% 36.2% 34.7% 30.7%
Avg Price 6.2 6.08 4.6 12.25 12.35 13.00 7.30 7.25 6.10

World Supply/Demand Summary

World S&D Summary, May 10, 2012, Million Metric Tons

Corn Soybeans Wheat
Crop Year 11-12 11-12 12-13 11-12 11-12 12-13 11-12 11-12 12-13
Report Date 10-Apr 10-May 10-May 10-Apr 10-May 10-May 10-Apr 10-May 10-May
Carryin 125.02 124.43 127.56 69.12 70.1 53.24 198.72 196.74 197.03
Production 864.97 870.45 945.78 240.15 236.87 271.42 694.32 694.64 677.56
Tot. Supply 989.99 994.88 1073.34 309.27 306.97 324.66 893.04 891.38 874.59
Feed 509.03 508.48 549.54 137.89 147.64 133.7
Crush 223.3 224.11 234.22
Other 358.26 358.84 371.47 29.9 30.03 30.92 548.87 546.71 552.77
Total Use 867.29 867.32 921.01 253.2 254.14 265.14 686.76 694.35 686.47
End Carryout 122.71 127.56 152.34 55.52 53.24 58.07 206.27 197.03 188.13
Stocks/Use Rat 14.1% 14.7% 16.5% 21.9% 20.9% 21.9% 30.0% 28.4% 27.4%

World Highlights

•World corn ending stocks were increased by nearly 5 MMT resulting in an increase in stocks-to-use, now projected at 14.7% for the current marketing year.

•The initial stocks-to-use estimate of world corn for the ‘12/‘13 marketing year came was estimated at 16.5%.

•World soybean ending stocks were reduced slightly for the current marketing year and were indicated to be unchanged for the ‘12/‘13 marketing year.

•World wheat ending stocks were reduced from the April estimate with stocks-to-use revisions being made downward for the current and next marketing years.

Market Strategy
This report is viewed as bearish for corn, bullish for soybeans, and neutral for wheat. Outside market forces and weather developments will drive these markets until the release of the June 30 actual plantings report. Although preliminary, the markets will trade these estimates for the ‘12/‘13 marketing year until adjustments are made. On today’s open, Dec ‘12 corn futures are $5.10; Nov ‘12 soybeans are $13.60; and July ‘12 SRW wheat is at $5.99 per bushel.

For technical assistance on making grain marketing decisions contact Carl L. German, Extension Crops Marketing Specialist.

Small Grain Disease Updates – May 11, 2012

Friday, May 11th, 2012

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

Stripe rust in wheat has been seen in both DE and MD this week. The outbreaks at this time are small and for most of the state wheat is past flowering, so the impact of increased rust development at this time should be minimal. Anyone who applied a fungicide such as Tilt, Prosaro, or Caramba at boot stage or heading will have 2-3 weeks of control, depending when it was applied and when stripe rust spores arrived from the south of us. We have not seen stripe rust in our region for several years. There have been population changes in the rust and it may be more aggressive than what we have seen in the past. We would be interested to know if you see it and what varieties get infected and the severity of the infection. Initially it might be found in a small area or several small areas but if the continued rain and cooler temperatures prevail it could spread quickly. If the wheat is past flowering, check fungicide labels for timing. See the next article for more information on stripe rust and effect on yield as well as fungicide choices.

 Close-up of stripe rust symptoms showing rust pustules in a line or stripe.

 Stripe rust on wheat.

Several more wheat samples were confirmed with Barley yellow dwarf virus. Most of the symptoms are mild but very widespread when it is found in a field. There is little impact on yield as best we know, but there is still much to learn about this virus in this region.

 Barley yellow dwarf showing reddening of flag leaf.

Wheat Disease Update
The following was written by Arv Grybauskas, Extension Plant Pathologist, University of Maryland and adapted for Delaware by Bob Mulrooney, Extension Plant Pathologist, University of Delaware

The risk of scab development this season has been very low and most of our wheat will be scab‐free or, at worst, have infection levels well below 10%. Vomitoxin levels should therefore be well below the 2 ppm threshold for acceptance at mills for most of the crop. The last few days, however, indicate that there are a couple of regions in the state that might still develop some scab. Much of the wheat in the hot spots in eastern Sussex County should be past flowering, and therefore past the label growth stage limitation for treatment with fungicides. However, there may be late planted fields or later developing varieties that can be treated. Leaf rust has been present on susceptible varieties since early spring but has been kept in check by unfavorable temperature or moisture conditions. It still has the potential to develop and spread if temperatures warm into the 80s at daytime and drop only to the mid‐60s at night as long as showers continue or dew and RH is high. Treatment of susceptible varieties may be warranted if leaf rust is present and is threatening to reach the flag leaves.

Stripe rust has also made an appearance this season. It was just confirmed in Dorchester and Caroline Counties in Maryland as well as in Delaware on Monday, May 7. These outbreaks are in small pockets (foci) in fields and their appearance is consistent with long‐distance spore transport from either NC or KY on storm fronts that came through about 2 weeks ago. Stripe rust, unlike leaf rust, requires cooler temperatures. In fact, at temperatures above 77°F lesions will stop producing spores and secondary spread is reduced, and at temperatures above 85°F the pathogen dies. The question now is, what is the potential damage and do I need to apply a fungicide? The short answer is, in my opinion, the worst‐case scenario for either rust disease (susceptible variety, and continuous disease favorable conditions through grain‐fill, and a focus of rust is present in the field now) would potentially produce a 10% yield loss. Realistically the weather will probably be less favorable sometime during grain fill so losses are more likely in the 1‐7% range (Table 1). For either rust disease it takes 7‐14 days to go through an infection cycle (infections giving rise to more spores that cause new infections) under ideal conditions. With that in mind, by the end of the grain‐fill period it is possible that the plants will look nasty (100% of the plants with 40 to 65% flag leaf severity) but between hard and soft dough stages this typically only produces 1 to 7% yield losses.

Table 1. Approximate Yield Loss in Relation to Severity of Rust on the Flag Leaf at Various Stages of Growth

Growth Stage Flag Leaf Area Infected with Rust
10% 25% 40% 65% 100%
Flowering 10 15 20 30 35
Milk 2 5 8 14 20
Soft dough 1 3 4 7 10
Hard dough 1 1 1 3 5

From: Hunger, B. and K. Jackson. Foliar Fungicides and Wheat Production in Oklahoma.

At this stage the only products that can be considered are triazole fungicides. The products registered for scab management, Prosaro and Caramba, are also effective against leaf and stripe rust. Rust susceptible wheat varieties that are still eligible for a fungicide application (pre‐ or just at flower) that are not at risk of developing scab may be sprayed with Folicur or a properly labeled generic tebuconazole product for rust control. Note that Prosaro, Caramba and Folicur have a 30 day Pre‐Harvest Interval as well as the growth stage restriction. Tilt has a 45 day PHI, and therefore would only be an option on earlier stage wheat where the risk of scab was low.

Soybean Rust Risk Assessment (ZedX, Inc. & PSU)

Friday, May 11th, 2012

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

The lower than normal rainfall observed has limited spread of soybean rust throughout the Southeast and South-central U.S. Soybean rust was recently identified in kudzu in Leon County, Florida on April 17. However, at this early point of the growing season, and with minimal infection across the South, the risk of long distance soybean rust spread to the north is minimal. The map below shows areas currently positive for soybean rust in northeastern Mexico and throughout the Gulf Coast area of the United States. A relatively mild winter likely contributed to more conducive overwintering conditions for rust on kudzu along the Gulf Coast. A drier last 30 days across the Southcentral along with drought conditions across the Southeast has made further rust spread unlikely in these areas.

Agronomic Crop Insects – May 11, 2012

Friday, May 11th, 2012

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

Alfalfa
In addition to checking for weevils feeding on re-growth, be sure to begin checking all fields for leafhoppers within one week of cutting. Spring planted fields should also be sampled since they are very susceptible to damage. Once the damage is found, yield loss has already occurred. The treatment thresholds are 20 per 100 sweeps on alfalfa 3 inches or less in height, 50 per 100 sweeps in 4-6 inch tall alfalfa and 100 per 100 sweeps in 7-11 inch tall alfalfa.

Field Corn
In addition to slugs and cutworms, be sure to sample fields for true armyworm larvae, especially where a grass cover or volunteer small grains were burned down at planting. As a general guideline, a treatment may be needed for armyworms if 25% of the plants are infested with larvae less than one-inch long.

Small Grains
Continue to scout fields for cereal leaf beetles, armyworms and sawflies. In unsprayed fields that have a history of cereal leaf beetle, we have observed a significant increase in activity this week. Cereal leaf beetle can cause the greatest economic loss from flowering through the soft dough stage. Once wheat reaches the hard dough stage, the beetle feeding damage generally has little effect on yield. It is important that you scout fields on a weekly basis until harvest for armyworm and sawfly larvae. We continue to find larvae in fields that have not been sprayed yet. Although sawflies and armyworm can attack and cause economic losses in both wheat and barley, in outbreak years the damage often occurs quicker in barley. Since populations of all of these insects vary from field to field, fields should be scouted to determine if economic levels are present. As a general guideline, if multiple insects are present, the threshold for each insect should be reduced by one third to one half. 

Garlic Bloat Nematode Found in Several Garlic Samples

Friday, May 11th, 2012

Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu and Karen Rane, Extension Specialist Entomology, University of Maryland rane@umd.edu

This must be a bad year for garlic because besides finding bulb mites we also have found garlic bloat nematode in several samples of damaged garlic. I wrote about this nematode last year and advised garlic growers to watch for it and to test any bad looking bulbs for it. This year growers are sending in their bad looking garlic bulbs and unfortunately many are infested with this nematode. The garlic bloat nematode Ditylenchus dipsaci can destroy a crop of garlic in one season. It probably came from Canada in garlic that was imported for food, but was planted as seed garlic. The problem then spread through distributors because there is no certification program for seed garlic and is it now widespread throughout New York. Symptoms of bloat nematode in garlic plants include: bloated, twisted, swollen leaves, distorted and cracked bulbs with dark rings (Fig.1).

Infested tissues become spongy, distorted and predisposes the plant to other problems like fusarium or white rot (Fig. 2) and bulb mites. These nematodes also can move to the inflorescence and remain in seeds for long periods of time in some plant species, i.e., beans, clover, and alfalfa where they are major sources of nematode dispersal. The nematodes can be spread around fields by equipment or on clothing and shoes. Garlic bloat nematodes can overwinter in soil or crop debris. If a grower has purchased or brought in new planting material over the last few years, especially if it came from Ontario or New York, you may have this pest. If you have not made any new introductions in a while you are probably safe. If you have garlic bulbs that look something like they do in figure 1 or 2 you should send a sample to a nematode laboratory for testing.

 

Fig. 1 The lack of roots on one side of plate and bulb deformation can be indicators of bloat nematode infection.

To prevent build-up of the nematode populations in a field, rotate away from any Allium crops (garlic, onions, and leeks) and control nightshades for at least 4 years. Another method to reduce levels of bloat nematodes in the soil is to keep the fields where garlic was grown moist, because bloat nematodes cannot survive for long periods in moist soils. They can persist for several years though, in dry soil and on dry plant residue. Bloat nematodes can actually survive better in dried crop debris than in soil.

Growers can use soil fumigants to reduce or eliminate the nematodes from infested areas of the field. Growers can also use bio-fumigant cover crops that can be planted after harvesting garlic. Mustard, sorghum-sudangrass have been shown to reduce nematode populations due to the bio-fumigant constituents they produce. Be sure to clean equipment and storage areas with meticulous sanitation techniques.

Fig. 2 Non-infested garlic bulbs (left) and infested garlic bulbs (right) with bloat nematode

Bulb Mite Found in Problem Garlic Fields

Friday, May 11th, 2012

Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu and Karen Rane, Extension Specialist Entomology, University of Maryland rane@umd.edu

Several garlic fields have been having problems the last few years with rotting bulbs. Some seedcorn maggot was found feeding on the bulbs and we thought this was the major problem. But damage continued beyond what the maggots could do. On a second look very tiny bulb mites were found in the damaged garlic. Bulb mites are a problem of garlic and sometimes of onion that usually goes unrecognized (as in this case). These pests can reduce stands, slow plant vigor, and increase post-harvest diseases by their feeding on the roots and the stem plate. Bulb mites have a very wide host range, but cause most of their damage to onions and garlic. These mite pests are usually not seen on the bulb and prefer crawling into crevices between the roots and stem plate.

The best way to determine whether these mites are present is to carefully dissect the region where the roots and bulb come together. The mites also could be under one or two layers of scales at the lower end of the bulb. There are usually other mites present, but with a hand lens the bulb mites usually can be identified from other mites.

The mite is bulb shaped with its legs moved forward and a bulbous rear end and many long fine hairs (Fig. 1). The mouthparts and legs are purplish-brown while the main body is creamy white. These mites have been described as looking like tiny pearls with legs. The mites are extremely small (from 0.02 to 0.04 inches) and are very slow moving. They are usually found in clusters underneath scales and at the base of the roots.

It is not just the direct feeding of these mites on garlic and onions that causes problems, but also their feeding allows pathogens to enter through the wounds they create. These wounds are very good entry points for pathogens like Fusarium spp., Sclerotium cepivorum (causes the disease white rot), and various soft-rotting bacteria. The white rot fungus does best in cool temperatures, and symptoms include white fungal growth on the stem or bulb with small, dark structures called sclerotia in the decayed tissue (Fig. 2). Early in the growing season, bulb mites can cause poor plant stands and stunted growth as they feed on the plants (Fig. 3). Infested plants easily can be pulled out of the soil because of the poor root growth. Later in the season, higher than normal amounts of soft rot and Fusarium dry rot may be seen because of the wounds caused by these mites (as we saw in a couple of the garlic fields).

Figure 1. Garlic bulb mites greatly magnified

Bulb mites survive in the soil on organic matter left behind from the previous crop. As long as there is decaying allium vegetable matter in the soil, bulb mites can survive in the field. The best way to control bulb mites is to allow the vegetation from the previous crop to breakdown before any new crop, especially garlic or onions are planted again. Low areas of the field that stay wet and have high levels of organic matter are especially prone to greater bulb mite survival. These mites may also come into a clean field on infested garlic cloves. The use of clean garlic clove seed or seed that has been hot water treated will control these pests. Effective hot water treatment will also, unfortunately, reduce bulb vigor.

 Figure 2. White rot (white fungus) with microsclerotia (arrows) in garlic stem

 Figure 3. Garlic plants damaged by bulb mite feeding and invasive fungi

Transplant Shock

Friday, May 11th, 2012

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

A number of watermelon fields have had issues with poor plant performance and plant losses after transplanting in the last 10 days. Transplant shock is most prevalent when there are cold, windy conditions after transplanting and when night temperatures drop below 50°F. Plant and planting conditions that increase the risk of plant shock include:

Poor hardening off. Plants that come directly out of greenhouses or that have just recently come out of houses are most at risk. A proper hardening off will include reducing fertilizer and water and exposing plants to outside conditions in a protected area. It takes a minimum of 5 days to harden off plants.

Different plant maturities. Younger plants are more susceptible to shock. In watermelons, pollenizers are often younger than seedless due to having more rapid growth. Pollenizers are often most susceptible to plant shock after transplanting.

Small root systems. Plants grown in small cell sizes have fewer roots and if rooting conditions after transplanting are not favorable, they will be at a higher risk of shock than plants with larger root systems.

Root bound plants. An opposite problem can occur where plants have been in trays too long and roots have become root bound. Root bound plants dry out more quickly and often do not send out new roots as quickly because many roots in the root ball have died or are growing in circles in the cell.

Root systems not fully formed. In cells of plant trays, if the plant has not produced sufficient roots, it will not pull out of the tray properly and roots will be damaged when extracting plants and plants will be more susceptible to shock.

Rough handling during transplanting. If transplant crews damage plants when pulling out of trays and when setting plants, there will be increased plant shock. This includes stem crushing or damaging roots when extracting plants.

Setting plants too low or too high. In the transplanting process, burying plants too deep where green stem or leaf tissue is below ground can lead to that tissue being exposed to rotting organisms. Conversely, if root systems exposed (set to high), they can dry out and cause plant loss.

Inadequate plant water. If there is inadequate water at transplanting, plants can dry out and losses can occur.

Too much fertilizer. Too much fertilizer in the transplant water or in beds near the plant can cause salt injury and plant losses.

Poor plant handling. Keeping plants in tight conditions such as plant trucks for long periods of time, in extreme heat conditions, or where they have no light for an extended period will weaken plants and when exposed to the direct sunlight after transplanting, losses can occur. Plants shipped in that have been in transit too long or where truck conditions were stressful (cold or hot) will have more risk of shock. Plants that have dried out before transplanting are also at risk.

MELCAST for Watermelons

Friday, May 11th, 2012

Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland; keverts@umd.edu

The weather based forecasting program MELCAST on watermelon will begin next week. MELCAST is a weather-based spray scheduling program for anthracnose and gummy stem blight of watermelon. If you received a report in 2011, you should automatically receive the first report next week. If your email or fax number has changed, please call us. If you do not receive a report and would like to, please call Karen Adams at (302)856-7303 and give us your name and Fax number or e-mail address. MELCAST also is available online – bookmark the site http://mdvegdisease.umd.edu/forecasting/index.cfm. Click on the watermelon picture.

To use MELCAST for watermelons, apply the first fungicide spray when the watermelon vines meet within the row. Additional sprays should be applied using MELCAST. Accumulate EFI (environmental favorability index) values beginning the day after your first fungicide spray. Apply a fungicide spray when 30 EFI values have accumulated by the weather station nearest your fields. Add 2 points for each overhead irrigation that is applied. After a fungicide is applied, reset your counter to 0 and start over. If a spray has not been applied in 14 days, apply a fungicide, reset the counter to 0 and start over. Please call if you have any questions on how to use MELCAST on your crop (Kate Everts at 410-742-8789).

Do not use Quadris, Cabrio or Flint on watermelons in Maryland or Delaware. Under low disease pressure, use Chlorothalonil (Bravo, etc.) applied according to MELCAST. Under high disease pressure alternate chlorothalonil with Pristine plus chlorothalonil, Folicur plus chlorothalonil, Inspire Super plus chlorothalonil or Luna Experience plus chlorothalonil applied according to MELCAST. If a severe disease outbreak occurs in your field, return to a weekly spray schedule.

Cucurbit Downy Mildew Fungicide Decisions

Friday, May 11th, 2012

Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland; keverts@umd.edu

Downy mildew on cucurbits has been a problem on Delmarva beginning in early July for the last few years. Good fungicides for management are available. However, last year in my trials, one of these fungicides, Presidio, was not as effective as expected. Looking ahead to your spray program, be careful not to rely on one fungicide class. It is difficult to know which fungicides will be effective here, because our population does not overwinter and is reintroduced from the South each year. Therefore use excellent resistance management practices to avoid allowing the pathogen to develop resistance and to improve the efficacy of your fungicide management program.

Fungicide Resistance management guidelines by crop are available online http://mdvegdisease.umd.edu/Disease%20Management/Fungicide.cfm and hard copies are available in Delaware at the county Extension offices.