Posts Tagged ‘17:12’

WCU Volume 17, Issue 12 – June 5, 2009

Friday, June 5th, 2009

PDF Version of WCU 17:12 – June 5, 2009

In this issue:

Vegetable Crop Insects
Late Blight Alert for Tomatoes & Potatoes
Increase in Soil Rots May Be in Store for Area Cucurbits
Pictures from Suspected Lightning Strike to Cantaloupe Field
Potato Disease Advisory #7 – June 4, 2009
Cucurbit Downy Mildew ipmPIPE
Salt Injury from Starter Fertilizer

Agronomic Crops
Agronomic Crop Insects
Corn and Wheat Disease Update
Soybean Rust Update
Grain Marketing Highlights

New Castle Co. Agronomic Crops Twilight Tailgate Session – June 10
On Farm Delaware Food Safety Training – Level I Certification – June 30


Late Blight Altert for Tomatoes and Potatoes

Friday, June 5th, 2009

Bob Mulrooney, Extension Plant Pathologist;

Tomato growers and potato growers should be aware that late blight has been diagnosed on home garden tomatoes in Northampton County on the Eastern Shore of Virginia and in NC and SC recently. As far as I know these have not been commercial fields, but growers should be on a preventative spray program of mancozeb (Dithane, Manzate, etc.) or chlorothalonil (Bravo). Should late blight occur locally, switch to a systemic fungicide targeting late blight such as Previcur Flex, Curzate, Ranman, Forum or other labeled fungicides. Be sure to check the label for rates, crop, and companion fungicides for resistance management. This current weather pattern had been ideal for late blight, frequent scouting is strongly advised.

Grain Marketing Highlights – June 5, 2009

Friday, June 5th, 2009

Carl German, Extension Crops Marketing Specialist;

Commodities Poised for Summer Rally
Several factors have come to light as possible reasons to expect a summer rally in the commodity markets. Included in these factors are: the CRB Index; the U.S. dollar index; potential performance of the Dow Jones Industrial Average; fund trading; and price seasonality. The Reuters/Jeffries CRB (Commodities Research Bureau) Index posted a bullish signal for early March 2009 and was followed by a secondary bullish signal in late April. This portends to the idea that the CRB Index should continue its rally over the summer quarter (June, July, August). Included in the mix of commodities the index tracks are corn, wheat, and soybeans.

Additionally, the U.S. dollar index has recently fallen through support near the 80.00 level, with the next level of support at 78.00. The nearby dollar index is currently at 79.57. A weaker dollar is expected to increase export demand for U.S. commodities over time. A weaker dollar is expected to lead to inflationary pressure on commodity prices, yet another reason to suggest a summer rally.

Another factor given for expecting commodities to rally over the summer is the economy. In February, the Dow Jones Industrial Average hit a low of 7,063. Since that time the Dow has rallied a little over 20 percent. The Dow could have further upside limited by inflation concerns. However, by late summer the Dow could move to its technical target of 9,330. An improving Dow generally portends to strength in commodity prices.

Fund trading (non-commercial speculative trading) has been gaining volume in recent weeks for corn, soybeans, and wheat. Non-commercial trading in wheat, for example, has taken wheat futures from a net short to a net long position. This has resulted in a pre-harvest contra-seasonal rally in wheat futures. Commodities can be expected to rally as long as non-commercials keep coming into the markets and adding to their positions.

Delayed row crop planting in the U.S. is expected to extend the seasonal rally for corn, which typically ends the first of June. Weather developments from here on will determine the length of time the rally can be expected to be extended. Soybeans tend to post their seasonal high in mid-July. The tight old crop soybean supply will continue to provide support while the new crop develops. For wheat, the first of June has marked the beginning of a seasonal rally that could last through March. The rally in wheat is likely to need assistance from a weaker dollar in order to improve exports. It is important to note that the wheat market generally reacts differently to market signals than do the corn and soybean markets. If one were to consider only the increasing forecasts for global wheat supplies and anemic U.S. exports for the current marketing year, then the current rally in wheat futures would not be expected and would not be happening.

Market Strategy
The outlook for commodity prices over the near term is bright. USDA will release the June Supply/Demand Report on June 10 and updated acreage numbers on June 30. Add to the declining acreage outlook the possibility of lower than expected yields for U.S. corn and reduced output for soybeans in the Southern Hemisphere, and prices have a reason to stay firm and rally.

Good pricing opportunities are currently available for new crop corn, soybeans, and SRW wheat. Seasonally, those opportunities are likely to remain available through mid-July. Weather developments and fund trading will determine the extent of the summer rally. Currently, Dec ’09 corn futures are trading at $4.64; Nov ’09 soybean futures at $10.63; and July ’09 SRW wheat futures are $6.37 per bushel.

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

Soybean Rust Update – June 5, 2009

Friday, June 5th, 2009

Bob Mulrooney, Extension Plant Pathologist;

On May 27 soybean rust was reported on kudzu in Decatur County, Georgia. On April 24, soybean rust was detected on kudzu in Gadsden and Leon Counties in Florida. The disease had been detected in both counties on kudzu earlier this year but had not been observed since January. Infections are still light, but the Georgia find was the earliest that rust has ever been detected in GA.


Corn and Wheat Disease Update – June 5, 2009

Friday, June 5th, 2009

Bob Mulrooney, Extension Plant Pathologist;

No need for me to tell you how bad the weather has been so far for corn. Stands are still being reduced by excessively wet soils and the Pythium and Fusarium damping-off that is occurring as a result of the wet soils. Fungicide treated seed, good drainage and some warm temperatures would help considerably in getting the plants out of the ground and growing.

Fusarium head blight or scab is being seen in some fields in Kent and Sussex counties. The occurrence and severity so far has been variable but, in general, I think we dodged a bullet this time. Our wheat for the most part was already in flower before the most favorable weather came for scab (Figure 1).

fusarium head blight 

Figure 1. Fusarium head blight or scab.

Take-all was diagnosed this week as well from two fields. Take-all is characterized by patches in the field that can vary in size but the wheat is generally stunted and the heads bleach out prematurely. Infected plants can be easily pulled out of the ground due to the extensive root rot that occurs. The other symptom is the dark streaking at the base of the stem (lowest node under the leaf sheaths), see Figure 2. Take-all can be controlled by rotating out of wheat for a year. However planting wheat followed by double crop soybeans followed by wheat is not an effective rotation for take-all control. Manganese levels also interact with take-all. Be sure that soil levels of manganese are adequate for the crop and check pH so that the managanese is available. High pH makes manganese unavailable.


Figure 2. Take-all symptoms on the lower nodes. Note lack of roots as well.

Tan spot (Figure 3) has been present for almost three weeks in wheat. This foliar disease can look like Septoria (Stagnospora) leaf and glume blotch. It is caused by the fungus Pyrenophora tritici-repentis.


Figure 3. Tan spot symptoms on wheat.

It has been widespread on Delmarva this season because of the amount of rainfall that we have had. It is too late for any control, but this disease is favored by wet, warm weather. Most of the spots are in the lower canopy and may reach the flag leaf before the plants begin to dry down. Applications of foliar fungicides at heading or earlier have been providing good control of this disease. At present most of the infection is in the lower canopy and the effect on yield should be minimal if the disease does not move up to the flag leaf or the leaf below the flag leaf.

Agronomic Crop Insects – June 5, 2009

Friday, June 5th, 2009

Joanne Whalen, Extension IPM Specialist;

Continue to sample for potato leafhoppers on a weekly basis. Although adults are the main life stage present, we will soon see the first nymphs. Although both life stages can damage alfalfa, the nymphs can cause damage very quickly. Once plants are yellow, 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.

Small Grains
We have received numerous reports and have seen a number of fields this week with high levels of armyworms in both wheat and barley that did not receive an earlier insecticide treatment. In some barley fields, significant head clipping has already occurred. As indicated in past newsletters, damage can quickly occur in barley. In many cases there is a mixture of worm sizes so the potential for head clipping is high, especially in barley. Be sure to scout all wheat and barley fields carefully and watch for head clipping. Since we are close to harvest for barley, the only control option at this point is Lannate which has a 7 day pre-harvest interval (PHI) between application and harvest. As a reminder, Warrior II and generic lambda-cyhalothrins products have a 30 day PHI between application and harvest. Be sure to read the label before applying any insecticide for the rate, days between last application and harvest and other restrictions.

Continue to sample for bean leaf beetles and grasshoppers. In the earliest planted and emerged fields, we have started to see an increase in activity for both insects. As barley is harvested and soybeans are planted, these fields will be especially susceptible to attack and grasshopper feeding can often cause stand loss. If stand reductions are occurring from plant emergence to the second trifoliate, a treatment should be applied. Although no precise thresholds are available, a treatment may be needed if you find one grasshopper per sweep and 30% defoliation from plant emergence through the pre-bloom stage. As a general guideline, a treatment may be needed for bean leaf beetle if you observe a 20-25% stand reduction and/or 2 beetles per plant from cotyledon to the second trifoliate stages. The Iowa State economic threshold for cotyledon stage is four beetles per plant. Once plants reach the V1 and V2 stages, their thresholds increase to 6.2 (V1 stage) and 9.8 (V2 stage) beetles/plant. These treatment thresholds should be reduced if virus is present or you suspected virus the previous season.

With the continued cool, wet weather, we continue to hear reports and have seen no-till soybean fields with significant slug damage. Although tillage will probably help and we have seen where it has at least helped to get soybeans out of the ground and growing this year, it may not be the total answer if populations are high and the weather does not turn around after planting. We have seen significant damage this spring in conventional corn fields where a cover was tilled under and then the field immediately planted. The only labeled, effective option for control is the use of the Deadline M-Ps. Be sure to read the new fact sheet from Ron Hammond from Ohio that provides excellent information on slug biology and management

Salt Injury from Starter Fertilizer

Friday, June 5th, 2009

Gordon Johnson, Extension Ag Agent, Kent Co.;

I recently looked at several snap bean plantings with symptoms of salt injury from starter fertilizer. Leaves had large areas that were dried from the margin inward, other areas were light green and showing signs of dessication. Symptoms were field wide and did not show up until after the plants had germinated and emerged. It was likely that fertilizer salts had moved toward the seedlings with water from rain and irrigation in high enough concentration to cause the injury. The grower had changed starter fertilizer to a higher analysis from previous years. Other crops were not affected. Caution should be taken with starter fertilizers, especially in crops that are sensitive to salts, such as beans. Choose low salt index fertilizers and limit the total amount of nitrogen and potassium (a general guideline is no more than 80 lbs total of N + K). Adjust fertilizer applicators to deliver the band no closer than 2″ to the seed and 2″ deep. If higher amounts of starter are required, move the fertilizer band farther from the seed.

Cucurbit Downy Mildew ipmPIPE

Friday, June 5th, 2009

Bob Mulrooney, Extension Plant Pathologist;

Because of the sudden and destructive nature of cucurbit downy mildew (Pseudoperonospora cubensis), growers need to be warned about a potential outbreak of the disease in their area. In addition, fungicide applications are far more effective if they are made before infection starts. The ipmPIPE forecasts give growers a site-specific risk assessment of disease outbreak 48 hours into the future. This forecast is available at Downy mildew is active in southern Texas as well as Florida and now has been reported in southern Georgia. It is a bit early for Delmarva but growers and fieldmen should get familiar with the site and some of the new features that have been added this season. Updates will be made in Weekly Crop Update but forecasts are made three times a week on Monday, Wednesday and Friday. Delaware is participating in the sentinel plot system associated with this effort. Plots are located at the REC near Georgetown and on the Experimental Farm here in Newark.


Upper leaf surface of cucumber with downy mildew.

Potato Disease Advisory #7 – June 4, 2009

Friday, June 5th, 2009

Bob Mulrooney, Extension Plant Pathologist;

Disease Severity Value (DSV) Accumulation as of June 4, 2009 is as follows:

Location: Shadybrook Farms, Little Creek, DE in Kent County.
Greenrow: May 1





Daily DSV

Total DSV

Spray Recs


P- days*




7- day interval










5-day interval





5-day interval





5-day interval





7-day interval





10-day interval


Maintain the recommended spray interval. At 300 P-days fungicide sprays will be needed to control early blight. Growers who do not want to rely only on the DSV calculations for scheduling fungicide applications should apply at least 1-2 sprays of mancozeb (Dithane, Manzate, Pencozeb, Manex II) or Bravo (chlorothalonil) before plants canopy down the row. At this point weekly fungicide applications would be suggested.

* P days- We use the predictive model WISDOM to determine the first fungicide application for prevention of early blight as well. The model predicts the first seasonal rise in the number of spores of the early blight fungus based on the accumulation of 300 physiological days (a type of degree-day unit, referred to as P-days) from green row. This should happen by next week. To date, 269 P-days have accumulated at the site. Once 300 P-days have accumulated, the first fungicide for early blight control should be applied. This usually occurs when rows are touching.

The Spray Recs column in the table is also generated by the WISDOM software program. This recommendation combines the DSV accumulation for late blight as well as the P-day accumulations for early blight and computes a spray recommendation. This is presented as a guide only. Spray decisions should be made with local conditions in mind and this information can help to determine if disease conditions are favorable.

For specific fungicide recommendations, see the Delaware Commercial Vegetable Production Recommendations.

If pink rot or leak is a concern and no pink rot fungicide was applied at planting consider applying one of the following when potatoes are nickel-sized and repeating 14 days later. Apply in as much water as possible (20-30 gal/A): Mefanoxam/chlorothalonil (Ridomil/Bravo) 2 lb/A, or Ridomil Gold/MZ 2.5 lb/A, or Ridomil Gold/Copper 2 lb/A. If Platinum/Ridomil Gold was applied at planting the label allows one foliar application of one of those products at tuber initiation if conditions warrant.

Pictures from Suspected Lightning Strike to Cantaloupe Field

Friday, June 5th, 2009

Emmalea Ernest, Extension Associate – Vegetable Crops;

Folks at the Carvel Research and Education Center spent a few days this week puzzling over a section of dead plants discovered on Monday in the cantaloupe variety trial. The early theory was that there was some sort of herbicide carryover issue but that didn’t make sense with the field history and some of the symptoms/evidence. After ruling out disease, aliens and sabotage we now suspect that the field was struck by lightning in the violent thunderstorm Georgetown got on Sunday morning.

Both cantaloupe plants and yellow nutsedge in the affected area showed symptoms (Figure 1) – making disease an unlikely explanation of the problem. The affected area is circular and approximately 50′ in diameter (Figure 2). Plant damage decreases as you move away from the center. At the center of the affected area the plastic mulch was damaged and the drip tape was split for approximately 30 ft (Figure 3). Cantaloupe and nutsedge plants near the center of the affected area were completely dead. Cantaloupe plants that were less affected have necrotic stems and necrotic patches on the leaves (Figures 4 & 5). The roots are partially or totally dead. Nutsedge plants had necrotic leaf tips and roots were partially or totally dead (Figure 6).

The cantaloupe trial will be replanted.

lightning struck lope and nutsedgeFigure 1. Affected cantaloupe and nutsedge plants.

 circle of destructionFigure 2. Circular area of damage in the field. Note damaged plastic at the center of the circle and that plant damage decreases toward the perimeter of the circle.

split drip irrigation lineFigure 3. Split drip tape and damaged plastic (replacement tape is beside the split tape).

 cantaloupe line-upFigure 4. Cantaloupe plants with varying levels of damage. Plants to the left are from the center of the affected area. The right-most plant is from outside the affected area.

lightning struck cantaloupe plantFigure 5. Close up of lightning damage to a cantaloupe plant. Note necrosis from the soil level, up the stems and petioles and out the leaves – presumably the path of the electric current through the plant vascular system.

nutsedge line-upFigure 6. Three yellow nutsedge plants from the affected area and one from another part of the field. Note damaged roots and burnt leaf tips on the three plants on the left.