Posts Tagged ‘19:3’

High Temperatures Can Affect Strawberry Yields

Friday, April 29th, 2011

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

Harvest of high tunnel plasticulture strawberries is well underway in the region and field harvest is beginning on plastic. Matted row strawberry harvest is still a few weeks off in most areas.

We have had several days in the mid 80s recently and this should remind growers that while the danger from frost should be over, effects of high temperatures can also greatly reduce strawberry productivity.

When daytime high temperatures reach a certain critical level, strawberries reproductive development will be affected. Flowering will be reduced or will stop altogether. The critical high temperature where flowering is affected and overall impact on flowering will vary with variety. Of the common strawberries being grown on plastic mulch in the annual system, ‘Camarosa’ is the most sensitive and will stop flowering and grow vegetatively when temperatures are above 86°F. ‘Chandler’ will handle somewhat higher temperatures. In matted row strawberry culture, it has been shown that strawberry size in ‘Earliglow’ is greatly reduced once temperatures reach the high 80s.

Growers wanting to maintain fruiting in years where May temperatures reach the high 80s or 90s should consider irrigating with overhead sprinklers during the day to cool plants (direct cooling and evaporative cooling). Use low volume sprinklers and set them to come on when air temperatures are above 85°F and come off when temperatures drop back below this level.

 

Transplant Disorders

Friday, April 29th, 2011

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

This is the time of the year when county agents are called to look at disorders in transplants being grown in greenhouses and when samples routinely come into our offices for diagnosis.

There are many diseases of vegetable transplants that can start in the greenhouse – fungal, bacterial, and viral. Diseases should be considered first when looking at transplants. Insects such as thrips, aphids, and whiteflies also can be a problem in greenhouses and should also be considered as causes of injury. They can cause direct damage and can be vectors of virus diseases.

However, many vegetable transplant disorders are not cause by pests. Some of the most common are:

Excessive Stretch and Leggy Plants
This is most commonly due to too high of temperature differential in growing houses (wide differences between day and night temperatures), excessive fertilization (especially with ammonium N fertilizers), and excessive watering.

Irregular Growth
This can have many causes including differences in seeding depth, differences in tray filling, differences in watering, differences in location in the greenhouse, irregular heating in the greenhouse (hot and cold spots), and differences in media to name a few.

Salt Injury
Plant desiccation and injury due to high salts occurs commonly when fertilizer rates are too high or when dumping occurs from slow release fertilizers at high temperatures.

Leaf Scorching
his can be due to salt injury also, but can occur when plants that are overcrowded are then spaced and exposed to full light or when very tender plants are put out to harden off in windy conditions.

Nutrient Deficiencies
Iron deficiencies are common if media pH rises above 6.3. Calcium and magnesium deficiencies are common if media pH drops below 5.2. Nitrogen deficiencies from under-fertilization are also common and also where initial nutrient charge in the media runs out.

Stunting
Poor plant growth or stunting most commonly is due to lack of nutrients in the media (media is missing initial nutrient charge). It also can be due to excessively cold greenhouse temperatures.

Ethylene Injury
Crops grown in greenhouses with propane or gas-fired unit heaters that are malfunctioning can be susceptible to ethylene injury. Ethylene (C2H4) is an odorless, colorless gas that acts as a plant hormone. Symptoms range from misshapen leaves and flowers, thickened stems, stunted growth, flower or leaf abortion to stem curling and wilting.

 

 

WCU Volume 19, Issue 3 – April 8, 2011

Friday, April 8th, 2011

PDF Version of WCU 19:3 – April 8, 2011

In this issue:

Vegetables
Vegetable Crop Insects
Managing Windbreaks in Vegetables
Spring Cover Crops for Vegetable Rotations
Water Testing for Produce Food Safety and Third-Party Audits, DPHS Lab Agrees to Do Testing
Fruit and Vegetable Growers Association of Delaware Hires a Special Programs and Outreach Coordinator
Mancozeb Label Updates

Fruit
Strawberry Angular Leafspot
Potential New Pest of Fruit – Spotted Wing Drosophila

Agronomic Crops
Agronomic Crop Insects
Barley Leafspot Diseases
Barley Frost Damage Hits in Kent Co.
Manganese Deficiency Can Worsen with Spring N Applications on Small Grains
Corn Planting in Cold Soils or No-Till Systems
Zinc Levels in No-Till and High Phosphorous/pH Soils
Grain Marketing Highlights

General
Endosulfan (Thionex) Cancellation Update
Top 10 Tips for Pesticide Spraying

Announcements
Wye Strawberry/High Tunnel Twilight Meeting – April 13

Weather

Top 10 Tips for Pesticide Spraying

Friday, April 8th, 2011

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

Bob Mulrooney submitted this article by Ohio State Extension and Purdue University Extension.

Farmers who want to make the most efficient use of pesticides should pay close attention to sprayer maintenance.

Erdal Ozkan, an agricultural engineer and spraying technology expert with Ohio State University Extension and the Ohio Agricultural Research and Development Center (OARDC), recommends following 10 common-sense tips that will help farmers improve sprayer performance:

1. Calibrate. Applying chemicals with a sprayer that is not calibrated and operated accurately could cause insufficient weed, insect or disease control, which can lead to reduced yields, Ozkan said. Check the gallon-per-acre application rate of the sprayer. This can only be determined by a thorough calibration. Use clean water while calibrating to reduce the risk of contact with chemicals. Read OSU Extension Publication AEX-520 for an easy calibration method: http://ohioline.osu.edu/aex-fact/0520.html

2. Mind the nozzle. How the chemical is deposited on the target is as important as the amount applied. Know what kind of nozzles are on your sprayer and whether or not their patterns need to be overlapped for complete coverage. Make sure the nozzles are not partially clogged. Clogging will not only change the flow rate; it will also change the spray pattern. Never use a pin, knife or any other metal object to unclog nozzles.

3. Avoid streaks. In addition to clogging, other factors such as nozzle tips with different fan angles on the boom and uneven boom height are the most common causes of non-uniform spray patterns. They can all cause streaks of untreated areas that result in insufficient pest control and economic loss.

4. Check the boom. Setting the proper boom height for a given nozzle spacing is extremely important in achieving proper overlapping. Conventional flat-fan nozzles require 30-percent to 50-percent overlapping of adjacent spray patterns. Check catalogs for specific recommendations for different nozzles.

5. Know actual travel speed and keep it as steady as possible. Increasing the speed by 20 percent may let you cover the field more quickly, but it also cuts the application rate by 20 percent. Similarly, a reduction of speed by 20 percent causes an over-application of pesticide by 20 percent – an unnecessary waste of pesticides and money.

6. Spray pressure and drift. Pay attention to spray pressure. Variations in pressure will cause changes in application rate, droplet size and spray pattern. At very low pressures, the spray angle will be noticeably narrowed, causing insufficient overlap between nozzle patterns and streaks of untreated areas. High pressure will increase the number of drift-prone droplets.

7. Avoid the dreadful drift. Spray drift wastes more chemicals than anything else. Don’t spray when the wind speed is likely to cause drift. Don’t take the risk of getting sued by your neighbors because of drift damage to their fields. Keep the spray pressure low if it is practical to do so, or replace conventional nozzles with low-drift nozzles. Use other drift-reduction strategies: keep the boom close to the target, use drift-retardant adjuvants, and spray in early morning and late afternoon when drift potential is less.

8. Be prepared. Carry extra nozzles, washers, other spare parts and tools to repair simple problems quickly in the field.

9. Calibrate again. Keep calibrating your sprayer periodically during the spraying season so it stays at peak performance. One calibration per season is never enough. For example, when switching fields, ground conditions (tilled, firm, grassy) will affect travel speed, which directly affects gallon-per-acre application rate.

10. Be safe. Read the chemical and equipment instructions and follow them. Wear protective clothing, rubber gloves and respirators when calibrating the sprayer, doing the actual spraying, and cleaning the equipment.

Grain Marketing Highlights – April 8, 2011

Friday, April 8th, 2011

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

USDA’s April Supply/Demand Report Runs Contrary to Pre-Report Expectations
USDA kept U.S. corn ending stocks at an estimated 675 million bushels by lowering projected feed use. Soybean ending stocks also remained unchanged at 140 million bushels because of lower export numbers. USDA also countered trade estimates by lowering wheat ending stocks even though the market had largely forecast higher ending wheat stocks. For Crop Production: http://usda.mannlib.cornell.edu/. For World Agricultural Supply and Demand Estimates (WASDE): http://www.usda.gov/.

U.S. Summary
USDA’s World Ag Outlook Board’s April numbers projected an increase in corn use for ethanol, which was offset by a reduction in expected feed and residual use. Corn going to ethanol increased 50 million bushels. U.S. corn for ethanol use is now projected at 5 billion bushels. U.S. corn feed and residual use was lowered by 50 million bushels compared to a month ago. Exports were unchanged at 1.95 billion bushels. The season average corn price is now estimated at $5.20 to $5.60 per bushel. U.S. corn ending stocks were left unchanged at 675 million bushels, the tightest level on record. The trade was expecting to see a decrease in corn ending stocks.

Soybean exports were lowered 10 million bushels from last month, due to increased competition from the Southern Hemisphere, and are now estimated at 1.58 billion bushels. The season average price was raised 15 cents on the low end and lowered 35 cents on the high end, now estimated at $11.25 to $11.75 per bushel. The trade was expecting to see a slight decrease in soybean ending stocks.

Wheat ending stocks were lowered slightly for the ‘10/‘11 marketing year to 839 million bushels, due to an increase of 4 million bushels in seed use. The season average farm price was lowered 10 cents per bushel on both ends of the price range, now estimated at $5.50 to $.5.70 per bushel. Pre-report trade estimates were expecting an increase in wheat ending stocks.

World Summary
World corn production was increased 1.2 million metric tons, with increases in production projected in Brazil, Paraguay and Uganda. Brazil’s production was increased 2 MMT. World corn ending stocks were reduced slightly, from 123.14 MMT to 122.4 MMT, above average pre-report expectations.

World soybean ending stocks were pegged at 60.94 MMT, up from 58.33 MMT last month, and higher than average pre-report expectations. The estimate for Brazilian soybean production was increased 2 MMT from last month, now estimated at 72 MMT. The Argentine production estimate was unchanged from last month at 22 MMT.

World wheat ending stocks were increased to 182.83 MMT, from 181.9 MMT a month ago. Australian and Canadian wheat production were left unchanged from the March report.

The next WASDE report will be released on May 11.

U.S. ENDING STOCKS (billion bushels) 2010-2011

Apr. Average High Low Mar. 2009-10
Corn 0.675 0.595 0.660 0.560 0.675 1.708
Soybeans 0.140 0.137 0.150 0.121 0.140 0.151
Wheat 0.839 0.861 0.893 0.835 0.843 0.976
Sorghum 0.032 0.036 0.040 0.032 0.037 0.041

WORLD ENDING STOCKS (million metric tons) 2010-2011

Apr. Average High Low Mar. 2009-10
Corn 122.43 121.03 122.90 118.50 123.14 196.77
Soybeans 60.94 58.94 61.00 57.50 58.33 60.67
Wheat 182.83 182.01 184.00 179.00 181.90 196.77

WORLD PRODUCTION (Million Metric Tons)

2010-2011 2009-2010
Apr. Mar. Apr. Mar.
Brazil corn 55.0 53.0 56.10 51.0
Argentina corn 22.0 22.0 22.80 21.0
Brazil soybeans 72.0 70.0 69.0 67.0
Argentine soybeans 49.5 49.5 54.5 53.0
Australia wheat 26.0 26.0 21.9 22.5
Canada wheat 23.2 23.2 26.8 26.5

Market Strategy
Fundamentally, nothing changed in this report. Although mostly neutral, the biggest negative in this report is likely to be viewed as the 2 MMT increase in world soybean ending stocks. Trader attention will now turn to weather developments impacting the 2011 U.S. and World row crop season. There remains no room for margin of error for 2011 crop production. Currently, new crop Dec ‘11 corn futures are trading at $6.45; Nov ‘11 soybean futures at $13.70; and July ‘11 SRW wheat at $8.05 per bushel.

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

Endosulfan (Thionex) Cancellation Update

Friday, April 8th, 2011

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

Endosulfan (Thionex): As a reminder for the 2011 season, all registrations for endosulfan were canceled as of December 2010. Although there is a phase out plan, there is not an existing stocks provision past the end dates. That means that you can no longer legally use it on a crop after the end date for that crop – so be sure to look at the link below since dates vary with crops. Also, there are a number of important changes to the Phase Out Labels, regarding REIs and PHIs that did not make it into the 2011 vegetable recommendations so be sure to read the label before making any applications. As a reminder, the Commercial Recommendations are only a reference — the label is law and you are required to read and follow the label before making any pesticide application.

As indicated above, the phase out plan includes end use dates for all currently labeled crops as well as additional mitigation measures during the phase-out period. In addition to mitigation requirements placed on endosulfan labels in previous years, EPA is requiring new mitigation measures for many crops during the endosulfan phase-out period. As stated in the Federal Register, “although these additional mitigation measures are designed to reduce worker risks, restricting and phasing out all uses of endosulfan will also address risks to wildlife and the environment.” Additional mitigation required during the phase-out varies by crop and includes measures such as: canceling aerial use and specifying other application methods, extending Restricted Entry Intervals (REIs), extending Pre-Harvest Intervals (PHIs), and reducing maximum single and/or seasonal application rates. As always, the label is the law so it will be critical to read all labels carefully to be sure you are following all restrictions.

Just one example of the changes – and there are many more so reading the label is critical – is that the Restricted Entry Interval (REI) on melons, cucumbers and summer squash is now 4 days; for pumpkins and winter squash it is 7 days. The PHI (pre-harvest interval) has also been increased on all cucurbits and differs between cucurbits so be sure to check carefully. In addition, Thionex can still be applied by air on melons only. It can only be applied by ground on cucumbers, pumpkins, winter squash and summer squash. (http://www.cdms.net/LDat/ld9P4000.pdf).

Be sure to read all labels and check the following Federal Register Link for more details on the specific end use dates and mitigation required. http://www.epa.gov/pesticides/reregistration/endosulfan/endosulfan-agreement.html

Zinc Levels in No-Till and High Phosphorous/pH Soils

Friday, April 8th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

I’ve noticed several soil tests recently that showed very low levels of zinc and at the same time high levels of available phosphorus and pH levels in the mid to upper 6 range. Growers should evaluate their most recent soil test reports especially if they are in continuous no-till systems. The combination of cold, wet soils in no-till production systems and high phosphorus, low zinc, and moderate to high pH levels can lead to some early season zinc deficiencies. Be sure to scout these fields frequently for symptoms of zinc deficiency.

The soil tests reports I’ve seen have shown zinc levels as low as 1.8 lb Zn/acre up to almost 5 lbs per acre and these values seem too low to me. Fields at these levels may need either a foliar zinc application once the corn is up and growing or a broadcast application of zinc sulfate to prevent early season zinc deficiency from injuring a corn crop. Another option is the use of an acidifying starter fertilizer possibly with a little zinc added to the fertilizer. The acidification of a narrow band near the corn seed can easily boost zinc uptake and prevent early season problems.

Corn Planting in Cold Soils or No-Till Systems

Friday, April 8th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

With a week gone in April already, many growers are anxious to begin planting corn. The long range forecast promises at least a few days of warmer temperatures in the coming week. Along with the threat of rain later next week, this will certainly encourage corn producers to begin planting their fields as soon as possible.

One thing growers need to keep in mind is that soil temperature lags air temperatures, sometimes to a large degree. Corn requires that the soil temperature be above 50°F for germination to proceed and growth to occur.

Another complicating factor is tillage. Soil in a no-till system tends to be wetter and cooler than that from a system incorporating some tillage. This translates into the need to keep seeding depth on no-till and early planted fields more shallow than for tilled and later planted fields. I would suggest maintaining a 1.25 to 1.5 inch seeding depth until soil temperature at a 3-inch depth begins to be consistently above 55 to 60°F.

Dr. Bob Nielsen at Purdue University has demonstrated that corn planted very early on cold soils where the temperature rises very slowly over a several week period takes as much as three weeks or more to emerge. Lengthy emergence periods lead to uneven emergence and large developmental differences between the early emerging plants and the later emerging plants. This uneven emergence can cause yield losses of 20 or more bushels per acre.

Once warm weather remains around long enough to significantly increase soil temperature, planting depth can be adjusted deeper to be sure the seed is placed in moist soil and is consistently deep enough for good root development. Wet fields and no-till fields will be the last ones in which to lower the planting depth to normal levels.

Barley Frost Damage Hits in Kent Co.

Friday, April 8th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu and Phillip Sylvester, Kent Co., Ag Agent; phillip@udel.edu

While checking out a barley field for possible manganese (Mn) deficiency problems, we discovered that the field had recently been damaged by freezing temperatures. Photos 1, 2, and 3 below show the typical whitening or bleaching of the leaf when temperatures drop below the critical level for barley at its current development stage. Photo 2 and 3 show the typical leaf tip bleaching but also show how freezing temperatures affect leaves differently depending on the stage of emergence of the leaf involved. Some leaves were affected only at the leaf tip while others were damaged around mid leaf leaving a whitened area in the middle of the leaf and green leaf at the tip and base of the leaf blade.

The question we can’t answer at this point with 100% certainty is whether the low temperatures caused pollen sterility in the developing seed head. The plants appeared to be at the Feekes 5 growth stage when the first node is just visible above the soil surface. We think that at this early stage damage will be limited to the leaf bleaching symptoms we observed. We won’t be able to know for sure until after heading when the anthers extrude from the florets and we can detect whether pollen release occurs. If pollen viability is impacted, the heads will not set grain and the heads will appear blank.

In the areas where Mn deficiency was observed, the leaf damage from the freezing temperatures was much worse causing significant injury to the barley plants (Photo 4). These plants will likely recover but yield will be much reduced.

Photo 1. Generalized tip burn on barley subjected to freezing temperatures following renewed spring growth and nitrogen application.

Photo 2. Leaf tip burn and mid-leaf frost injury showing stage of leaf emergence at the time of freezing temperatures.

Photo 3. Close-up view of leaf injury caused by freezing temperatures on barley. The growing point is just above the soil surface at this stage of growth.

Photo 4. Close-up view of severity of frost damage on Mn deficient plants.

Barley Leafspot Diseases

Friday, April 8th, 2011

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

As you scout your fields at this time of year it is often easy to find scattered brown spots in barley. Sometimes in wheat and rarely in barley, a minor disease called Ascocyta leafspot can be found on winter damaged tissue that can resemble Septoria leafspot but the plants grow out of it once warm weather arrives. The other brown spot that can be seen now is the early symptoms of net blotch. This is a very common leafspot of barley in our region. Severity is determined by the weather (it likes cool and wet) and the susceptibility of the variety. High nitrogen fertilization early will also favor development. Spot blotch rarely gets severe enough here to warrant fungicide applications. The symptoms that develop on barley can vary depending on the variety of the fungus present (there are several forms or isolates of this fungus) and the barley genetics. Later in the season we see the spot blotch form of net blotch (two leaves on the left) more frequently than the classic net blotch symptom seen on the two leaves on the right in the picture below.

Two leaves on left- spot blotch form of net blotch, on the right classic net blotch symptoms

Sometimes the only symptom development is a small brown spot or fleck that never enlarges or blights a leaf. This is thought to be the barley resistant reaction to the fungus infection.

The picture above, taken two days ago, shows the early symptoms on leaves before jointing has occurred. Typically, as the season warms the older infected leaves at the base of the plants will die and the new leaves may or may not develop more symptoms depending on the weather.