Posts Tagged ‘18:4’

WCU Volume 18, Issue 4 – April 9, 2010

Thursday, April 8th, 2010

PDF Version of WCU 18:4 – April 9, 2010

In this issue:

Vegetables
Vegetable Crop Insects
Considerations Following a Wet Year
Break in the Weather
Fusarium Wilt on Watermelons
Considerations for Herbicide Selection

Fruit
Success with Blueberries
Pear and Apple Fire Blight: Maryblyt Predictions Can Aid in Disease Management

Agronomic Crops
Agronomic Crop Insects
Agronomic Crop Diseases
Grain Marketing Highlights

Announcements
Free Tour of Horse Barn Facilities at University of Delaware – April 19
Is It Arthritis or…Is It Lyme Disease? Arthritis and Farming Workshop – April 30
Local Farmers Wanted for Western Sussex Farmer’s Market

Weather

Grain Marketing Highlights

Thursday, April 8th, 2010

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

Ahead of the Report
Two days ahead of what many are expecting to be a bearish USDA supply/demand report due to U.S. and World ending stock estimates, an extremely positive development entered the fray. Rumors of Chinese interest in U.S. corn and DDGs resulted in sharply higher trade yesterday as buying from both sides of the market emerged. Spillover support from the corn market led soybean contracts to solid gains on Wednesday. The nearby May contract closed above both the 20-day and 50-day moving averages, which could trigger additional noncommercial buying this week. Noncommercial short-covering led to a second consecutive session of double-digit gains for wheat. This sets up the possibility of a bullish reversal on the continuous weekly chart Friday. Tomorrow morning (Friday, April 9) USDA will release the April Supply/Demand report. Although no major surprises are expected, it is possible that USDA will increase U.S. and World ending stocks of corn; increase U.S. and World ending stocks of soybeans; with world ending stocks for all wheat being closely watched to see if stock estimates actually increase or decrease due to production decreases in some key growing areas.

The rumor gave life to an otherwise dismal looking outlook for the commodities market. Yesterday’s rally occurred in spite of a stronger dollar, weaker energy prices, and a weaker Dow. The rumor may also have been buoyed by a wet forecast for the Western Corn Belt for next week likely to cause delays in field work.

Big Crops Get Bigger
An old adage in grain marketing says that ‘big crops get bigger’. Many are expecting the Southern Hemisphere soybean crop to get bigger in tomorrow’s release of USDA’s production forecast. Pre-report production forecasts for Brazil are estimating 2010 soybean production at 67.1 to 67.4 million metric tons. Argentine soybean production estimates are projected at 55 MMT. In March USDA projected Brazilian soybean production at 67 MMT and Argentine production at 53 MMT. Brazilian corn production was forecast at 51 MMT and Argentine corn production was forecast at 21 MMT in the March projections. Although the Brazilian corn production estimate is unchanged from last year, the Argentine corn production estimate is running on the order of 6 to 7 MMT larger than last year. This in turn will make more corn available to the world market.

Market Strategy
Rumors of Chinese demand for U.S. corn will need to be confirmed. However, if confirmed the positive impact upon corn prices would be most welcome providing some impetus to kick starting the seasonal rally for corn and soybeans. Obviously the U.S. is not the only supplier of corn to the world market. In a typical year Argentina is the 2nd largest corn exporter with approximately 6 to 8 MMT available for export. The U.S. exported 61.91 MMT in ‘07/08; 47.18 MMT in ‘08/‘09; and the March estimate projected exports at 48.26 MMT in the ‘09/‘10 marketing year. Argentina exported 14.8 MMT in ‘07/‘08; 10.10 MMT in ‘08/‘09; and the March estimate projected Argentine exports at 12.0 MMT for the ‘09/‘10 marketing year.

On Thursday, Dec ‘10 corn futures closed at $3.88; Nov ‘10 soybean futures at $9.41; and July ‘10 SRW wheat futures at $4.88 per bushel. Since last week, Dec corn futures improved 11 cents; Nov soybean futures improved 27 cents; and July SRW wheat futures improved 12 cents per bushel.

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

Agronomic Crop Diseases

Thursday, April 8th, 2010

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

Wheat
Wheat development is later than normal due to the adverse wet weather conditions beginning back in the fall. It is not too early to remind growers, consultants and fieldmen about several resources that are available for monitoring Fusarium head blight (scab). Two websites are available, the first is the scab predictor site http://www.wheatscab.psu.edu/ with the risk map tool and the second is a new site called Scab Smart.

Scab Smart Web Site Can Help With Head Scab Management
The U.S. Wheat and Barley Scab Initiative (UWBSI) has a Web site that provides farmers with information on how to manage Fusarium head blight, commonly known as scab.

Scab Smart is designed to serve as a quick guide to the integrated strategies that result in optimum reduction of scab and its primary associated mycotoxin, deoxynivalenol (DON).

On the site, producers can access information by management strategy or wheat class. Scab Smart’s content will be updated on an ongoing basis as new management information becomes available.

The site can be accessed through this website http://www.scabsmart.org

Stripe Rust and Leaf Rust
On another topic, stripe rust and to a lesser extent leaf rust, are increasing in the South. There have been reports of greater than normal infection levels of stripe rust in Louisiana, Texas and Oklahoma. It is never easy to predict if it will make it to Delmarva. Stripe rust has not been a problem in Delaware since 2006 and 2007. When it has occurred it has had variable effects on wheat depending how mature the crop is when the disease appears. Most of the damage in the past has occurred in the northern parts of the state. When scouting wheat later in the season keep this disease in mind. Alerts will be given if it gets closer to us. Generally applications with a triazole containing fungicide made at flag leaf emergence through heading will provide good control.


Stripe rust on wheat.

Corn
There have been growers with increasing southern root knot nematode populations in field and sweet corn, especially when pickling cucumbers, soybeans, and lima beans have been in a rotation. The best way to reduce root knot nematodes in corn is with an at-planting application of Counter 15G. The data I have seen for seed treatments that might be effective for root knot have not been consistent at this time. They are definitely worth looking at but how effective they will be is still a question in my mind.

Agronomic Crop Insects

Thursday, April 8th, 2010

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

Alfalfa
Be sure to watch for economic levels of alfalfa weevil and pea aphids. When sampling for aphids and weevils, collect a minimum of 30 random stems throughout a field and place them top first in a white bucket. For aphids, you want to count the number present per plant as well as any that have dislodged from the stem into the bucket. As a general guideline, you should consider a treatment in alfalfa less than 10 inches tall if you find 40-50 aphids per stem. The treatment threshold for alfalfa 10 inches or taller in height is 75-100 per stem. Although beneficial insects can help to crash aphid populations, cooler temperatures will slow their activity. As a general rule, you need one beneficial insect per every 50-100 aphids to help crash populations. For alfalfa weevil, you will also want to record the number of weevil larvae per stem. The following thresholds, based on the height of the alfalfa, should be used as a guideline when making a treatment decision: up to 11 inches tall – 0.7 per stem; 12 inches tall – 1.0 per stem; 13 – 15 inches tall – 1.5 per stem; 16 inches tall – 2.0 per stem and 17 – 18 inches tall – 2.5 per stem.

Wheat
Low levels of aphids and cereal leaf beetle adults can be found in fields throughout the state. Since we are past the prime time for barley yellow dwarf transmission (fall transmission is the most important), the next important time to consider aphid management in small grains is at grain head emergence. Since cereal leaf beetle populations are often unevenly distributed within the field, it is important to carefully sample fields so that you do not over or under estimate a potential problem. Eggs and small larvae should be sampled by examining 10 tillers from 10 evenly spaced locations in the field while avoiding field edges. This will result in 100 tillers (stems) per field being examined. Eggs and larvae may be found on leaves near the ground so careful examination is critical. You should also check stems at random while walking through a major portion of the field and sampling 100 stems. The treatment threshold is 25 or more eggs and/or small larvae per 100 tillers. If you are using this threshold, it is important that you wait until at least 50% are in the larval stage (i.e. after 50% egg hatch). You will also want to access the Virginia AG Pest Advisory http://www.sripmc.org/Virginia/ for a good article entitled Is Wheat at Greater Risk to Cereal Leaf Beetle?

We are also finding low levels of winter grain mites in no-till wheat fields. This is a cool weather mite so be sure to watch fields for this pest, especially with the predicted cooler temperatures for next week. The following is an overview of this pest written by Dr. Ames Herbert from Virginia Tech: “Winter grain mites attack small grains, including wheat, barley, and oats. The mite also infests and damages legumes, vegetables, ornamental flowers, cotton, peanuts, and various weeds. Adult mites are about 1 mm long, black, with red legs and are fast moving. They quickly run to ground cover when you approach plants. As the name implies, they are winter pests. There are two generations per year. The first develops from over summering eggs. Development begins after the onset of favorable temperature and moisture conditions in late September and October with populations peaking in December and January. The second generation develops from eggs laid by the first generation reaching maximum infestation density in March and April. Populations then decrease as temperatures exceed the range of tolerance. The females of this generation lay aestivating or over summering eggs. Temperature and moisture are the most important factors influencing mite development and abundance. Cool rather than warm temperatures favor their development. Egg laying is heaviest between 50° and 60°F; the optimum conditions for hatching are between 44° and 55°F. When temperatures drop below or rise above these ranges, the mites stop feeding and descend to the ground or burrow into the soil. Mite activity in the spring drops rapidly and the eggs fail to hatch when the daily temperature exceeds 75°F. Aestivating (over summering resting stage) eggs do not hatch in the fall until rains provide adequate moisture. On hot, dry days it may be necessary to dig into the soil to a depth of four or five inches to find mites. The mites are not harmed by short periods of sleet or ice cover or by ground frozen to a depth of several inches. The larvae become very active soon after hatching and begin to feed on the sheath leaves or tender shoots near the ground. The larvae as well as the adults feed higher up on the plants at night or on cloudy days. As the sun rises, the mites descend the plants and seek protection during the hot part of the day on the moist soil surface under foliage. If the soil is dry and there is little foliage cover, they dig into the soil in search of moisture and cooler temperatures. At sunset and thereafter the plants become covered with feeding mites where, with the aid of a searchlight, they can be observed feeding at all hours of the night. Dispersion from field to field may occur by transportation of aestivating eggs or mites on grain stubble or leaves, on soil adhering to implements that are moved about, or on forage or straw carried from infested fields in livestock feeding operations. Aestivating eggs may also be transported on debris by wind, and local distribution may occur by adult migration. Such migrations to grain fields may take place from fencerows or other uncultivated areas. Heavily infested fields appear grayish or silvery, a result of the removal of plant chlorophyll by mite feeding. When high infestations feed on the plants for several days, the tips of the leaves exhibit a scorched appearance and then turn brown, and the entire plant may die. These mites do not cause the yellowing characteristic of spider mite feeding. Many of the infested plants do not die, but become stunted and produce little forage or grain; damage on young plants, however, is more severe than on large, healthy ones. Damage may also be greater in plants stressed by nutrient deficiencies or drought conditions. There are two types of damage to the small grains, namely, reduced amount of forage throughout the winter and reduced yields of grain in the spring and summer. Cropping practices have a marked effect upon the occurrence and damage caused by the winter grain mite. Injury by this mite may be prevented by crop rotation, that is, by not planting small grains more than two years in succession.”

Pear and Apple Fire Blight: Maryblyt Predictions Can Aid in Disease Management

Thursday, April 8th, 2010

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

Adapted from an article in Ky Pest News April 6, 2010 #1224 by John Hartman, Extension Plant Pathologist, University of Kentucky.

Flowering pears (Pyrus calleryana), grown in many landscapes, are in full bloom in most of Delaware. Pears grown for fruit in backyards and orchards in the region are also in flower now. Fire blight can be a devastating disease of nursery and landscape flowering pears and can also damage pears (both Asian and European) in fruit orchards.

Fire blight primary infections occur during bloom. During warm spring weather, the causal bacteria (Erwinia amylovora) grow on the surface of flower parts such as the stigma. After several warm days, high populations of bacteria become available to be washed by rainfall or even heavy dew into the nectaries at the base of the flowers. Once inside the flower, the bacteria continue to grow, killing the fruit spur and spreading into the subtending twigs and branches. Disease build-up from these infections leads to shoot infections, the most noticeable part of this disease, which appears later.

This year, a new version of a computer program called Maryblyt has become available to help nursery growers and orchardists make decisions to manage fire blight disease. This new version of the program, called Maryblyt 7, utilizes Windows-based computers and was updated by plant pathologists Dr. A. R. Biggs (Tree Fruit Research and Education Center, Kearneysville West Virginia) and Dr. W. W. Turechek, (USDA-ARS, Florida). They have indicated that it is free for the downloading by growers, extension agents and crop advisors.

Go to the following link http://www.caf.wvu.edu/kearneysville/Maryblyt/index.html to download a copy of the new Maryblyt 7 program.

This is a good time for growers to get the program running for the 2010 season. Growers can enter the data themselves and the program automatically provides a chart and graph of fire blight status. Growers only need to provide date, growth stage, daily maximum and minimum temperatures, and rainfall (or heavy dew) for their nursery or orchard. Weather data are entered into the program starting at green tip (perhaps sometime between March 21-24 this year) so weather data from recent weeks will need to be found. Growers wanting weather data specific to their orchard or nursery can purchase a maximum/minimum thermometer and a rain gauge at the hardware store. By knowing when infection is expected, preventive orchard and nursery applications of streptomycin can be used in a timely way.

Success with Blueberries

Thursday, April 8th, 2010

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

There has been an increase in interest with blueberry production in Delaware over the past 5 years. Blueberries can be a very profitable crop, especially for growers that direct market. As a perennial shrub-like crop, blueberries will take 5 or more years to come into full production but can be productive for decades. It is critical therefore to make sure that plants get off to the right start. Blueberries have exacting soil modification requirements that must be addressed. They are native to areas with acid soils that have high organic matter in the surface but with sand below and with water relatively close to the surface. However, they do not tolerate waterlogged soils.

There are 5 key factors critical to establishing blueberries.

1) Acidify the soil. Blueberries require acid soils with a pH in the 4.5-5.2 range (target 4.8). Most of our cultivated soils have pHs much higher than this. Therefore soils must be acidified. The material commonly used to acidify soils is elemental sulfur. However, sulfur must be converted by microorganisms to release the acidity so it acidifies only when soils are warm. Plan one year ahead of time to acidify the soils. On a sandy loam soil, about 1000 lbs of sulfur per acre are required to lower the pH to the desired level. You should not plant until the soil has been acidified.

2) Provide good drainage. Make sure that water drains away from the planting site and does not collect. It may be necessary to make low, wide ridges to improve drainage and move excess water away from plants. Avoid planting in sites that are poorly drained or that have high water tables in the winter.

3) Increase organic matter in the area that is to be planted prior to planting. This is commonly done through the addition of materials such as peat moss mixed directly into the planting hole (mix at one gallon of peat with backfill soil for each plant during planting). You may also use other materials such as composted saw dust, bark fines, or other partially rotted materials as long as they are acid (have low pHs). You can use up to half by volume of these materials mixed with soil in the hole. Do not use manures, high pH composts, or spent mushroom soil. You may also choose to modify the entire planting strip before planting. Apply 2-4 inches of these organic materials (such as composted sawdust or bark fines) and work them into the soil in a 3-6 foot strip where the blueberries are to be planted.

4) Mulch immediately after planting with a 4 inch layer of organic material. Common materials are aged sawdust or bark mulch. This mulch is critical to protect the shallow roots and provides additional organic matter as it decomposes (reapply as necessary).

5) Install drip irrigation and provide irrigation water through the drip as needed. Blueberries do best in moist (not wet) soil conditions. Drip tubing should be thick walled for long term use and should be placed under the mulch.

Considerations for Herbicide Selection

Thursday, April 8th, 2010

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

All herbicide labels state maximum allowable rates and rotational restrictions. These restrictions are in place for various reasons including potential for injury to rotational crops, the potential for rotational crop to pick up herbicide residue, and/or environmental issues. All of these restrictions have equal weight and need to be observed. In the past few years, there has been much more scrutiny of pesticide records, not only what the current crop was treated with, but also the previous crops. Vegetable growers have had to significantly alter their plans because of the previous year’s herbicide use. When someone asks about rotation, it is not adequate to simply think about crop injury.  You also need to consider issues such residues and environmental issues and this information is on the herbicide label. Read and follow the label.

Fusarium Wilt on Watermelons

Thursday, April 8th, 2010

Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland; keverts@umd.edu and Emmalea Ernest, Extension Associate – Vegetable Crops; emmalea@udel.edu

Production changes over the past decade have resulted in increasing levels of watermelon Fusarium wilt in Delaware and Maryland. Fusarium wilt is easily recognized by the characteristics of wilting of one vine or the whole plant (Figure 1 A and B) and the red to brown discoloration of the vascular systems (Figure 2).

Figure 1. Single vine runner wilted mid-season (A) and wilted plants at harvest (B).

Figure 2. Vascular discoloration within the cut watermelon stem (Image from A. P. Keinath, Clemson Univ.).

The fungus that causes Fusarium wilt, Fusarium oxysporum f.sp. niveum, was successfully managed for many years through a combination of cultivar resistance in seeded cultivars, rotation, and fumigation. However, the cultivation of seedless cultivars, which have lacked resistance in the past, and the loss of the use of methyl bromide as a fumigant have resulted in an increase in Fusarium wilt. In addition, the pathogen population has shifted to a more virulent type. The good news is that many watermelon breeding programs are working to develop seedless cultivars with resistance to the virulent races present here in Delaware and Maryland. A study conducted at the University of Delaware’s Research and Education Center in 2009 evaluated several seedless cultivars which had been reported to have resistance to race 1. Some cultivars performed well (Table 1) including Abbott & Cobb lines ACR6277TSS, ACX4674T, Seedway’s Sweet Delight and Seminis’ Olympia. We have confirmed that race 2 is present in the field which may have caused the poor results we observed on other lines that also had some resistance. Through a grant from the Delaware Department of Agriculture Specialty Crops Block Grant, we will continue our evaluations in 2010. Stay tuned for an announcement of a field day opportunity to see our results.

Table 1.Watermelon Cultivars Evaluated for Resistance to Fusarium Wilt in 2009

Cultivar Source Wilt Incidence (%)* Yield
7 July 21 July Fruit no. per plot t/ha
Ruby Siegers 36 b** 52 a 3.5 e 3.0 a
Indianna Seedway 68 a 46 a 6.5 de 2.9 a
Melody Seedway 29 bc 27 b 15.0 bcd 8.5 a
Majestic Seminis 13 bc 16 bc 16.8 bc 14.5 a
Sugar Heart Siegers 11 bc 14 bc 16.8 bc 25.0 a
ACX5727 FR Abbott & Cobb 18 bc 13 bc 14.8 bcd 13.3 a
ACR6177TSS FR Abbott & Cobb 5 c 9 bc 20.3 abc 21.7 a
Olympia Seminis 7 c 9 bc 12.5 cde 12.2 a
ACX5117T FR Abbott & Cobb 16 bc 7 c 23.3 ab 31.1 a
Sweet Delight Seedway 7 c 7 c 15.0 bcd 18.7 a
Matrix Seedway 29 bc 5 c 16.5 bc 26.1 a
ACX4674T FR Abbott & Cobb 7 c 5 c 26.8 a 28.9 a
Apollo Seminis 16 bc 5 c 16.8 bc 17.9 a
ACR6277TSS FR Abbott & Cobb 7 c 4 c 22.3 ab 34.0 a
P>F 0.0012 0.0001 0.0012 0.0515

*  Percent of plants that were wilted or dead.

**Mean values in each column and year followed by the same letter are not significantly different at P = 0.05 based on Fisher’s protected least significant different test.

Break in the Weather

Thursday, April 8th, 2010

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

March was a very poor month for early spring crops due to cool, wet conditions. In most areas there were only 3-6 days in March where soils were suitable for planting. This limited March plantings of peas, potatoes, cabbage, spinach, and other early season vegetables. With the break in the weather, unseasonably high temperatures, and wind, much drying has occurred allowing for land preparation and planting into good soil conditions. Pea and potato planting is progressing, plastic is being laid for early warm season vegetables, early sweet corn has been planted and the first sweet corn plantings have emerged.

With the warm temperatures, growers are reminded that the likelihood that we will see a return to cold weather and will see frost again in April is still very high. At Georgetown, our last frost in 2008 and 2009 was on April 17. This means that growers should wait until the last week in April for the first plantings of frost sensitive crops such as melons and tomatoes or be prepared to use row covers for frost protection on those crops if planting earlier. For most of Delaware, there is still a 60-70 % chance of a frost through the third week in April; however, the risk of a major freeze event from this point on is very small.

Considerations Following a Wet Year

Thursday, April 8th, 2010

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

From the spring of 2009 through the winter of 2010, we received record amounts of precipitation. The following are some considerations for vegetable production following a wet year.

● Check your pHs. The pH of soils during wet years often drops more than in normal periods. Be most concerned where fields have a “borderline” overall pH in the 5.7-6.0 range. Often there will be areas in those fields with much lower pHs. Specifically check your sandiest areas, which leach the most, and headlands where there may be overlaps in nitrogen application (ammonium and urea fertilizers drop the pH). These areas may have spots with pHs well below 5.5. You should also check the pH of areas in the field that were wet or waterlogged. Wet field areas initially drop in pH due to fermentation of organic matter by microorganisms in anaerobic conditions as well as an increase in carbon dioxide dissolved in the soil water forming a weak acid. However, the pH may subsequently rise in flooded soils due to reducing bacteria which consume the acidifying hydrogen. When these areas dry out, they may drop in pH again due to several soil processes. Therefore it is hard to predict the pH of wet areas and separate samples should be taken after they have drained.

● Take time to note and mark out drainage problems and take measures to address them. Drainage problems in fields can have severe impacts on vegetable crops through waterlogging that limits oxygen for roots and through increased activity of soil borne pathogens that thrive in wet conditions. This past year offered the “worst case scenario” and drainage issues are obvious. Use this information for planning purposes.

● Nitrogen carryover this year is minimal and should not be counted on. Fields with no cover crops or poor stands of cover crops will provide very little recycling. Nitrogen recommendations will have to be modified accordingly.

● Compaction from a number of sources is evident in many fields. In particular, rutted areas from field crop harvest operations last fall will need to be addressed with targeted tillage this spring.