Posts Tagged ‘19:23’

WCU Volume 19, Issue 23 – August 26, 2011

Friday, August 26th, 2011

PDF Version of WCU 19:23 – August 26, 2011

Vegetables
Vegetable Crop Insects
Vegetable Disease Update
Food Safety and Flooded Vegetable Fields
Flooding and Vegetables
Nitrogen Fertilization After Flooding

Fruit
Sure Looks Like Brown Marmorated Stink Bug Damage – But It Isn’t

Agronomic Crops
Agronomic Crop Insects
Charcoal Rot Identified in Corn
Soybean Disease Update
Considerations for Weed Control in Winter Wheat
Grain Marketing Highlights

Announcements
Mid-Atlantic Precision Ag Equipment Day – August 30, Denton, MD
DSU Small Farms Program Niche Market Field Day & Open House – August 30, Smyrna, DE
UD Corn Hybrid Trial Tour & Twilight – September 1, Dover, DE
UD Lima Bean Twilight – September 15, Georgetown, DE

Weather

 

Grain Marketing Highlights – August 26, 2011

Friday, August 26th, 2011

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

Demand Slackens as Supply Concerns Loom
USDA’s next scheduled release of monthly supply and demand estimates for the U.S. and World will be on September 12. Adjustments are expected for 2011 planted acres and yield estimates for U.S. corn and soybeans. The market has recently traded in anticipation of the September report. Yield and planted acreage estimates are expected to drop further in the September report. This raises the usual question, how high can prices go based upon the expected downward revisions in U.S. corn and soybean production? The answer to that question can be summed up by simply stating that the size of the adjustments will determine whether prices need to bid higher from current levels in order to ration supply. In their July estimates USDA projected total use for U.S. corn for the 2011/12 marketing year at 13.5 billion bushels. Production was estimated at 13.470 billion bushels, 30 million bushels less than projected total use. This means that any downward revisions made in the September report will be price positive to U.S. corn and soybeans. Whether the revisions are considered to be already factored into prices on release day of the report or not will depend upon trader expectations going into the report (the rumor) and what USDA says the projected production is (the fact). An old marketing adage says to ‘buy the rumor, sell the fact’. The results of the Pro Farmer crop tour will soon be tabulated. Those results may garner the attention of commodity traders for a time but not for long, all eyes will be upon the September 12 report.

USDA Export Sales Report 08/25
Pre-report estimates for weekly export sales of soybeans ranged from 27.6 to 33.1 million bushels. The weekly report showed total old-crop and new-crop export sales of 24.1 million bushels, with old-crop sales 3.9 million bushels, bringing the yearly total to 1.552 billion bushels, above USDA’s demand projection of 1.495 billion bushels. Total shipments of 10.4 million bushels were below the 17.8 million bushels needed this week. This report is considered bearish.

Pre-report estimates had weekly corn export sales at 19.7 to 27.6 million bushels. The weekly report showed total old-crop and new-crop export sales of 20.7 million bushels, with old-crop sales of 15.1 million bushels, bringing the yearly total to 1.907 billion bushels, above USDA’s demand projection of 1.825 billion bushels. Total shipments of 32.5 million bushels were below the 44.4 million bushels needed this week. This report is considered bearish.

Pre-report estimates for wheat export sales ranged between 14.7 to 27.6 million bushels. The weekly report showed total export sales of 12.8 million bushels, below the 16.1 million bushels needed this week to stay on pace with USDA’s 1.1 billion bushel demand projection. Total shipments of 17.2 million bushels were below the 20.9 million bushels needed this week. This report is considered bearish.

This report should be considered bearish.

Market Strategy
Those that have corn and soybean bushels to sell are currently sitting in the driver’s seat, with new crop prices trending higher. Generally speaking, it is a good idea to reward market rallies with sales. New crop corn and soybean futures made new highs this week due to U.S. production concerns. Advancing sales on a portion of the remaining bushels would seem to make sense. Basis levels could widen drastically in the event USDA were to exceed expectations in revising the crop size down. Currently, Dec ‘11 corn futures are trading at $7.38; Nov ‘11 soybeans at $13.87; and July ‘12 SRW wheat at $8.16 per bushel.

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

 

Considerations for Weed Control in Winter Wheat

Friday, August 26th, 2011

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

As we approach fall and planting wheat, it’s time to consider options for weed control. A few species have become more troublesome, and I attribute a lot of this to the way we have been approaching weed control. Most herbicides go out in the spring with nitrogen. While this might be acceptable for many fields, it is often not the most effective application timing. When splitting nitrogen applications in the spring, neither one are a great timing for herbicide application. The first nitrogen application is applied when the wheat is beginning to “green-up” after the winter, so this is before the wheat is actively growing (also means that the weeds are not actively growing). The second nitrogen application is after tillering and just before stem elongation (means weeds have grown considerably in the spring from first application of nitrogen and much taller than 3”, and wheat growth prevents good coverage; both reducing the effectiveness of the spray). This is contrary to all recommendations which are: spray small weeds that are actively growing and achieve good coverage.

UD Weed Science Program has been looking at herbicide applications to winter wheat in the fall. Typically these treatments are going out in middle to late November. Some of the reasons this approach have been successful are:

1. Weeds are more susceptible in the fall. As I pointed out they are smaller and actively growing. Furthermore, fields with heavy poultry litter applications or excess nitrogen tend to have lots of weed growth in the fall and this contributes to even worse control in the spring.

2. Fall applications match better with weed development. As noted weeds are smaller the earlier they are sprayed. Furthermore, most annual species will progress to flowering early in the spring which can reduce herbicide performance as well.

3. Weed emergence is primarily in the fall. Some emergence occurs in the spring, but most occurs in the early fall. Fall emerging weeds are more detrimental to yield than spring emerging weeds. And, if there is significant spring emergence, then a herbicide treatment with the second split of nitrogen will be beneficial for these small seedlings.

4. Fall herbicide applications are not influenced by temperature as much as spring applications. It is usually late into March that we start to get consistent temperatures above 55°F. In the fall, heavy frosts have occurred by mid November, but soil temperatures allow for active plant growth during the days. Therefore, we have better environmental conditions for control in the fall than early spring.

5. Coverage is better with fall applications. See notes above

6. Spreads out the workload. And if all the best planned strategies do not get implemented in the fall, you have a back-up plan for treating in the spring (albeit not as effective as fall).

I realize some spring herbicide applications are necessary such as: wild garlic control (but Harmony Extra can be applied with the second nitrogen applications); other perennial species that emerge in the spring (Canada thistle or bulbous oatgrass); or late planted fields when the crop may not reach the stage for safe application. But fields with a history of poor weed control, should be targeted with fall applications.

Next week will be a review of available herbicides for fall applications.

 

Soybean Disease Update – August 26, 2011

Friday, August 26th, 2011

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

Sudden death syndrome was diagnosed on soybean from Sussex County. This was an unexpected find since I associate SDS with cool, wet seasons. The only control for SDS is to plant resistant varieties, or, if susceptible soybeans are to be planted, double crop soybeans are rarely infected. I would not expect this to be widespread but we did see it so be on the lookout for symptoms.

Foliar symptoms of SDS

 Infected root on the left with diseased leaf compared to healthy stem and leaf.

Charcoal rot was also confirmed on soybean as well as corn. Soybeans are killed by the fungus resulting in dead, stunted plants in irregular patterns in the field. Symptoms are worse on full season early maturing varieties (Maturity Group III and possibly early Group IV’s). The diagnostic symptoms are the ashy gray stems and lack of roots. Splitting the lower taproot and stem longitudinally with a knife reveal the best diagnostic feature which is the presence of the small black microsclerotia in the pith and often the cortex. Charcoal rot is favored by hot, dry weather and is common in Delaware soils that have been heavily cropped to soybeans over the years. The tiny sclerotia overwinter in the soil and it just takes the right environmental conditions for the disease to occur. There is no usable resistance in soybeans to charcoal rot. The stress during flowering and early pod set triggers development of symptoms if that coincides with hot, dry, stressful weather. Most initial infections occur during the seedling stage and remain latent until flowering and later. Later maturing soybeans typically flower and set pods most years when conditions are less stressful and escape the yield reducing effects of the infection. Double crop soybeans are rarely affected by charcoal rot here in DE. Two year rotation will help reduce microsclerotia levels in the soil but if corn is used at least three years is suggested. Longer rotations would be better if they could be implemented.

 Split soybean stem showing the charcoal gray discoloration in the pith with microsclerotia.

 Close up of gray pith from the presence of the tiny microsclerotia of the fungus that causes charcoal rot.

Charcoal Rot Identified in Corn

Friday, August 26th, 2011

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

Charcoal rot was identified in corn this week. Charcoal rot caused by the fungus Macrophomina is a common disease in soybean during hot, dry seasons. Occasionally it is seen in corn causing a stalk rot that in the early stages can look like the common stalk rots that we see here such as Diplodia, Fusarium and Giberella stalk rots. However when the stalk is split the characteristic sign of charcoal rot is the abundant small reproductive structures (sclerotia) inside the rind, especially on the vascular bundles. The inside of the stalk especially the lower 3-4 nodes are gray black giving it the name charcoal rot. Hybrids that have good resistance to other stalk rots often have some resistance to charcoal rot but the hot, dry conditions and early senescing of stalks can lead to infection and symptom development. Harvest in a timely manner to avoid lodging problems.

Charcoal rot on corn. Note the black sclerotia attached to the vascular bundles in the pith. That is the best diagnostic feature for identifying charcoal rot.

 

Agronomic Crop Insects – August 26, 2011

Friday, August 26th, 2011

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

Soybeans
Be sure to continue to scout carefully for earworms during the next few weeks. Also, as we get closer to harvest be sure to check all labels for the days between last application and harvest.

Threshold levels of corn earworm continue to be found in fields throughout the state but they are not present in every field. Although we can find various sizes of larvae, in most cases they are still relatively small. In addition they are being found in some full season (especially where canopy is not closed) and double crop fields so the only way to know if you have an economic level will be to scout. If fields were already sprayed, be sure to watch for newly hatched larvae. With the sustained flights, there could be a new hatch of small larvae.

Since last week’s report, we also are starting to find an increase in stinkbugs, especially in full season fields. Like corn earworms populations, the levels as well as species vary from field to field depending on your location in the state. In Sussex County, the predominant species are native green and brown stink bugs. From the Harrington area through New Castle County, the brown marmorated stink bug can be found in the mix. In some fields, there continue to be hot spots of brown marmorated stink bugs with the highest populations generally still along woods edges. You will need to continue to scout for stinkbugs in fields that are in the pod development and pod fill stages. Economic damage is most likely to occur during these stages. You will need to sample for both adults and large nymphs when making a treatment decision. Available thresholds are based on beans that are in the pod development and fill stages. We are currently following the same guidelines that are being used in Virginia. Thresholds are based on numbers of large nymphs and adults (native green and/or brown stink bugs), as those are the stages most capable of damaging pods. As a general guideline, current thresholds are set at 2.5 per 15 sweeps in narrow-row beans, or 3.5 per 15 sweeps in wide-row beans.

Similar to 2010, there are fields with high levels of whiteflies. Although we have limited experience with whiteflies in our area, as far as we know, whiteflies have not been a problem in the past even when we have seen what folks describe as “clouds of whiteflies”. They are related to aphids (that is they are in the same order of insects) and so can cause yellowing on the leaves if populations are high enough. Damage is most likely to occur when beans are stressed. The following link provides pictures of whiteflies and some additional comments regarding whiteflies in soybeans: http://bulletin.ipm.illinois.edu/article.php?id=832.

For more information on what is occurring in Virginia, you will want to look at the Virginia Ag Pest Advisory: http://www.sripmc.org/Virginia/.

Sure Looks Like Brown Marmorated Stink Bug Damage – But It Isn’t

Friday, August 26th, 2011

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

Over the last few weeks growers have given me damaged pears that at the time I said looked like brown marmorated stink bug damage. Pears on the outside had pits in them where it looked like the bug had fed at one time (Photo 1). When the fruit is cut open there is a brown spot deep inside the pear that looks like brown marmorated stink bug (BMSB) feeding damage (Photo 2). But this spot differs from BMSB feeding in a couple of ways. First it is extremely hard, it is almost impossible to get a knife through it. Almost all of the BMSB damaged pears and apples and other fruit where I have seen a brown spot may be pithy or mealy or firm, but it has never been really hard. Second no yeast was found associated with the spot. In almost every case of BMSB feeding resulting in a dark spot in the fruit we have found yeast. And thirdly there was no stylet wound found in the damaged areas. I have found that if the cut is made into the fruit to the brown spot that the brown spot will then swell in a short time and stick up from the surface of the cut fruit (Photo 2).

The most likely cause of the damaged pear fruit appears to be Stony Pit disease, but even this we are not entirely sure. One problem is that the causal agent of Pear Stony Pit has yet to be isolated, but it can be transmitted by grafting and therefore a virus seems to be the most likely suspect, but no one knows for sure. Insect vectors or infected seed have not been documented as transmission factors for the virus.

The symptoms usually start about three weeks after petal fall, when dark green spots form on the fruit. The areas around these spots continue to grow, but the spots themselves do not. This results in misshapen fruit with pits (Photo 1). Pits often become necrotic and the fruit beneath becomes hardened (Photo 2). If fruit is heavily pitted it may become so hard that it is difficult to cut with a knife. Cracking of the bark, stunting of trees and chlorotic vein-banding have also been reported. One of the very odd things about this “disease” is that symptoms on fruit vary from season to season as well as severity. Trees that show symptoms one year may have no pitted fruit the following years. This type of scenario resembles damage more from BMSB feeding than a virus disease, which makes the diagnosis that much more difficult.

The best management practice seems to be to select virus-free trees for planting. Some of the most severely infected cultivars include Bosc, Comice, and Seckel, while less pronounced symptoms are found on Hardy, Conference, Forelle, Howell, Old Home, Packham’s Triumph, Bartlett, and a few other cultivars.

This is NOT MEANT TO SAY BMSB has not caused severe damage in the mid-Atlantic on fruit and vegetables because it has, just that fruit damage can be attributed to BMSB (as I did) when it was not the causal agent. Stony Pit seems to be fairly common this year in pears and any damaged-pitted fruit should be examined carefully.

Photo 1. Pear fruit with deep dimple in center caused by Stony Pit disease

Photo 2. Dimple area cut open showing extremely hard, raised brown spot

Nitrogen Fertilization After Flooding

Friday, August 26th, 2011

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

With heavy rain expected this weekend, flooding can be expected in some vegetable fields. In addition to nitrate leaching, there is potential for significant denitrification losses in saturated soils.

In fields that have been waterlogged for several days, nitrogen fertilization will be critical to helping plants recover.

Root growth and function is impared by flooding and therefore nitrogen uptake will be limited. N levels in soils will be low due to leaching and denitrification. Nitrogen should be applied as soon as soils have drained. Foliar N fertilization may be of great benefit after flooding as root systems recover.

In flooding studies at the University of Florida byYuncong Li, Renuka Rao and Stewart Reed, they tested several N fertilizers both as dry applications and foliar applications for their effectiveness in recovering flood-damaged vegetable crops and found that potassium nitrate performed the best, urea the second best, and calcium nitrate the third best. Liquid urea-ammonium nitrate solutions should perform similarly to urea as a foliar application and as a sidedressing where crops are still small enough to get equipment through. Limit foliar applications to less than 3% total salt solutions. In plasticulture vegetables that have been flooded, foliar applications will be necessary until the beds have dried out enough to allow for fertigation through the drip system.

Flooding and Vegetables

Friday, August 26th, 2011

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

There is still considerable acreage of watermelons, sweet corn, pumpkins, beans, cabbage, potatoes, and other fresh market vegetable crops in the field on Delmarva. On the processing side, the majority of lima beans have yet to be harvested and there are significant acres of pickles, snap beans, and other processing crops in the field. Many of these crops will be at risk in the coming days due to hurricane Irene.

A late summer hurricane or tropical storm with both wind damage and excess rain can cause major issues in vegetable crops, most notably:

● Damage due to flooded soils in all vegetable crops

● Increased disease incidence in all vegetable crops

● Lodging damage in crops like sweet corn

Other articles will address diseases in with excess rainfall. I will focus on flooding effects on the physiology of vegetable plants.

Flooded and Waterlogged Soils
In flooded soils, the oxygen concentration drops to near zero within 24 hours because water replaces most of air in the soil pore space. Oxygen diffuses much more slowly in water filled pores than in open pores. Roots need oxygen to respire and have normal cell activity. When any remaining oxygen is used up by the roots in flooded or waterlogged soils, they will cease to function normally. Therefore, mineral nutrient uptake and water uptake are reduced or stopped in flooded conditions (plants will often wilt in flooded conditions because roots have shut down). There is also a buildup of ethylene in flooded soils, the plant hormone that in excess amounts can cause leaf drop and premature senescence.

In general, if flooding or waterlogging lasts for less than 48 hours, most vegetable crops can recover. Longer periods will lead to high amounts of root death and lower chances of recovery.

While there has not been much research on flooding effects on vegetables, the following are some physiological effects that have been documented:

● Oxygen starvation in root crops such as potatoes will lead to cell death in tubers and storage roots. This will appear as dark or discolored areas in the tubers or roots. In carrots and other crops where the tap root is harvested, the tap root will often die leading to the formation of unmarketable fibrous roots.

● Lack of root function and movement of water and calcium in the plant will lead to calcium related disorders in plants; most notably you will have a higher incidence of blossom end rot in tomatoes, peppers, watermelons, and several other susceptible crops.

● Leaching and denitrification losses of nitrogen and limited nitrogen uptake in flooded soils will lead to nitrogen deficiencies across most vegetable crops.

● In bean crops, flooding or waterlogging has shown to decrease flower production and increase flower and young fruit abscission or abortion.

● Ethylene buildup in saturated soil conditions can cause leaf drop, flower drop, fruit drop, or early plant decline in many vegetable crops.

Recovering from Flooding or Waterlogging
The most important thing that you can do to aid in vegetable crop recovery after floods or waterlogging is to open up the soil by cultivating (in crops that still small enough to be cultivated) as soon as you can get back into the field. This allows for oxygen to enter the soil more rapidly. Nutritionally, sidedress with 50 lbs of N where possible.

In fields that are still wet, consider foliar applications of nutrients. According to Steve Rieners at Cornell “Use a low salt liquid fertilizer to supply 4 to 5 lb nitrogen, 1 lb phosphate (P2O5) and 1 lb potash (K2O) per acre. Since nitrogen is the key nutrient to supply, spraying with urea ammonium nitrate (28 % N solution) alone can be helpful. These can be sprayed by aerial or ground application. Use 5 to 20 gallons of water per acre. The higher gallons per acre generally provide better coverage”. As with all foliar applications, keep total salt concentrations to less than 3% solutions to avoid foliage burn.

Food Safety and Flooded Vegetable Fields

Friday, August 26th, 2011

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

In produce fields that are flooded, another consideration for growers is food safety. The following is a good article on the subject from Steve Reiners at Cornell University.

FLOODS AND FOOD SAFETY
There are two types of flooding. The first is more typical and occurs after a heavy downpour when fields become saturated and water pools on the soil surface. This type of flooding can reduce yields and even kill plants but usually will not result in contamination of produce with human pathogens.

The second type of flooding is more severe and seen less often. Standing water in fields that is runoff from stream/river overflows will more likely be contaminated with human pathogens. Unless flooding was light and there is no danger of bacterial contamination from floodwater, do not use fruits and vegetables that were ready for harvest at the time of flooding. Some fruits and vegetables are more susceptible than others to bacterial contamination.

Leafy vegetables (such as lettuce, cabbage, mustard, kale, collards, spinach, and Swiss chard) along with strawberries are more likely to be contaminated. Silt and other contaminants may be imbedded in the leaves, petioles, stems, or other natural openings of fleshy structures and can be difficult to remove. Do not use if mature when flooded.

Root, bulb, and tuber crops such as beets, carrots, radishes, turnips, onions, and potatoes are less susceptible to bacterial contamination. Produce with a protected fruit or impervious outer skin such as peas, melons, eggplant, sweet corn, or winter squash may be contaminated on the surface.

It is extremely important that produce be properly washed to reduce contamination.

To control postharvest losses, it is recommended that produce be washed in chlorinated water before storage or shipping (see table below). The wash temperature should be about 10°F warmer than the produce temperature to ensure that decay organisms are not sucked into the tissue. Since chlorine is most effective at a slightly acidic pH, it is important that wash water is buffered to adjust the pH to between 6 and 7.

Chlorine in the wash water is often inactivated when the wash water becomes dirty. Use filtering devices to remove soil and organic material, and check the chlorine concentration often. Produce should be subjected to the chlorinated wash from one to ten minutes. After it is removed, allow it to drain for several minutes before packing. NOTE: Leafy vegetables at or near harvest that were flooded with stream/river overflows should not be harvested or consumed. Chlorinated wash water will not eliminate likely human pathogens on their surface.

Amount of sodium hypochlorite to add to wash water for 50-150 PPM dilution.

Target ppm

ml/L

tsp/5 gal

cup/50 gal

Sodium Hypochlorite, 5.25%

50

1.0

3.66

0.75

75

1.4

5.5

1

100

1.9

7.25

1.5

125

2.4

9

2

150

2.9

11

2.25

Sodium Hypochlorite, 12.75%

50

0.4

1.5

0.33

75

0.6

2.25

0.5

100

0.8

3

0.66

125

1.0

3.75

0.8

150

1.2

4.5

1