Volume 11, Issue 3                                                                                                    April 11, 2003

Fruit

 

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

 

Section 18 Approved for Provado on Stone Fruits.

Provado 1.6F has been approved for use on peaches, nectarines, plums and apricots in Delaware to control aphids, including the green peach aphid, a vector of Plum Pox Virus.

 

A maximum of 4 applications at the rate of 5-6 fl. oz. of product/A (0.06-0.08 lbs. a.i./acre) of Provado 1.6F may be made by ground equipment.  No more that 24 ounces of the product (0.32 lbs a.i.) may be applied per acre per year.

 

 

 

Vegetables

Watermelon Promotion Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu

 

The National Watermelon Promotion Board has received approval from the USDA for a new logo that emphasizes watermelon as the “lycopene leader in fresh produce.”  Research has indicated that lycopene, a cartenoid, may help reduce the risk of prostrate cancer and heart disease.  Another good reason for consumers to buy Delmarvalous watermelons.

 

 

 

 

 

Wet Conditions and Potato Weed Control Decisions Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu

 

The continuing wet conditions have obviously delayed much of the potato planting progress.  In some cases, the weather may have eliminated the opportunity for pre-emergence treatments of herbicides.  However, there are excellent post-emergence materials available. 

 

If no pre-emergence materials were applied, a Matrix (rimsulfuron) and Sencor (metribuzin) combination will control many grass and broadleaf weed species.  While the Matrix rate is 1 ounce/acre, a reduced rate of Sencor (metribuzin) at 1/3 lb./acre should be used when mixed with Matrix.  Use non-ionic surfactant at 1 quart per 100 gallons of spray.  Always check the label for additional instructions and restrictions.  This must be applied before the potatoes are 14 inches tall.  Of course, the earlier the application, the better the weed control.

 

The post-emergence grass materials, Select or Poast, can also be used as separate applications to control escaped grasses.

 

 

Vegetable Diseases Kate Everts, Extension Plant Pathologist, Univ. of MD and Univ. of DE; everts@udel.edu

 

 

Ozone injury on watermelon.

Bifacial necrosis of old watermelon leaves.

(Mid-August.)

 

Photo taken from the USDA-ARS, North Carolina State University Air Quality Research Unit at the following address:

http://www.ces.ncsu.edu/depts/pp/notes/Ozone/o3waterm.html

 

Ozone Damage in Watermelons. 

Ozone injury to watermelons is common in Delaware and on the Eastern Shore of Maryland.  Symptoms include flecking, premature chlorosis, and necrosis (yellowing and tissue death) of crown leaves.  In severe cases, the leaves will become skeletonized.  A recent study conducted by Dr. Gerald Holmes (NCSU) showed that seedless cultivars tended to be more tolerant of ozone damage than seeded cultivars.  He did not find a relationship between cultivar fruit size or shape and ozone damage.  Crimson Sweet, Sentinel, and Tri-X-Palomar were more sensitive to ozone than the average cultivar tested.  Mardi Gras, Revolution, SeedWay 4502, HMX 8914, TRI-X-313, Millionaire, Freedom, and Millennium were more tolerant of ozone damage than the average cultivar tested.  Cultivar tolerance to ozone damage is the only available management tool we have for this problem.

 

 

 

Field Crops

 

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

 

Supply and Demand Report Viewed as Uneventful

Commodity analysts are reporting no big surprises from the April 10th Supply and Demand report. The numbers most watched in this report were ending stocks for U.S. corn, soybeans, and wheat. The ending stocks for all three commodities were well within pre-report estimates.

 

Corn ending stocks are now listed at 1.009 billion bushels vs. the average trade guess of 999 million bushels. Ending stocks for corn were reported to be 5 million bushels less than last month's estimate.

 

Soybean ending stocks are down to 145 million bushels, vs trade guesses ranging from 125 to 150 million bushels. Soybean stock estimates are down 15 million bushels from last month.

 

Wheat stocks are down 20 million bushels from last month. The decrease in wheat stocks, now placed at 445 million bushels is due primarily to a 25 million bushel increase in domestic feed and residual use and a 5 million bushel increase in imports on the supply side.

 

CBOT Launches Mini Agricultural Futures Contracts

The Chicago Board of Trade launched CBOT mini corn, wheat, and soybean futures contracts on Monday, April 7. The trading hours for these 1,000 bushel contracts will be from 9:30 a.m. to 1:45 p.m. These contracts replace the mini contracts that were formerly traded at the Mid-America Commodity Exchange. If interested in getting further information contact Carl German, clgerman@udel.edu

 

 

 

Is It Too Late to Apply Nitrogen to Small Grains? - Richard W. Taylor, Extension Agronomist; rtaylor@udel.edu ; Derby Walker, Jr., Sussex County Extension Ag Agent; derby@udel.edu

 

The question being raised after the most recent period of bad weather is if it still is worth while fertilizing small grains.  An important component of the answer is the determination of the stage of growth of the crop.  Where you haven’t been able to apply fertilizer yet, you should take the opportunity to scout a field for the crop’s growth stage while you wait for it to dry.  Examine a number of plants across the field and determine growth stage by looking closely at the primary tillers on each plant.  Check tillers to see if you can feel a swelling that indicates node development.  Another way is to pull back leaf sheaths to expose the growing point and see if more than one or two internodes (the space between two nodes) are present.  Also, observe how far above the soil surface the growing point is.  The jointing stage of growth begins when the first node appears above the soil surface and jointing progresses as more and more nodes occur above the soil surface until boot stage when the seed head can be felt within the leaf sheaths.

 

Once the space between the nodes begins to lengthen and pushes the growing point that ends in the seed head above the soil surface, the likelihood of doing at least some damage to the crop by driving across a field to spread fertilizer is great.  After several internodes are visible, the chance of having a large impact on yield by applying nitrogen (N) diminishes.  Another helpful indicator will be the intensity or greenness of the crop or signs of N deficiency on the lower leaves.  The number of leaves per plant showing N deficiency symptoms relates to the amount of N stress and that corresponds to loss of yield potential.  When combined with plants at later stages of development (late jointing or early boot), the damage caused by N stress reaches the point where additions of N will no longer boost yields enough to be profitable.  The earlier you can apply N the more yield response you are likely to see.  By boot stage, N will have little impact on yield potential although it can still influence the grain N content.

 

Another question asked is whether wheat that recently came up will yield?  This question is harder to answer because wheat requires a period of cold temperatures to change it from vegetative state to a reproductive state.  Winter wheats require more cold weather than spring wheats and southern varieties of winter wheat can be switched to a reproductive state by fewer days of cold than varieties developed further north.  The problem with deciding if a field will move to the development of grain (yield) is knowing when the crop germinated enough for the cold temperatures to begin the process of vernalizing the crop and switching it to a reproductive state.  With a microscope or a very good hand lens (and good eyesight), you might be able to dissect plants and identify the developing panicle if it has switched to the reproductive state.  At the growing point even when it is very tiny, you can identify the developing panicle or seed head since it looks like a miniature wheat head.  Even if you find that the crop has vernalized, the yield potential is an open question.  Experience suggests wheat that emerges in late February can produce 50 to 60 bu/A but we’ve not had experience with wheat emerging later than that date.

 

Avoiding Leaf Burn from UAN on Small Grains - Richard W. Taylor, Extension Agronomist; rtaylor@udel.edu; Derby Walker, Jr., Sussex County Extension Ag Agent; derby@udel.edu

 

Several years ago Ron Mulford, the farm manager for University of Maryland’s Popular Hill Research Farm, passed along to Derby Walker the following dilution values for 30 percent UAN (urea-ammonium nitrate) solution.  The dilution should be enough to prevent the leaf burning of small grains when liquid nitrogen (N) is broadcast applied under warm conditions (60˚F and higher). 

 

If you have to apply UAN under warm conditions, you may want to follow the guidelines below to possibly reduce the potential for leaf burn.  Since weather conditions may be forcing many producers to apply N much later than they like, preventing even the mildest of stress such as the temporary leaf burn UAN can cause can be worth the extra effort.

 

Table 1.  Approximate dilutions for UAN solutions when topdressing small grain to reduce the potential for leaf burning under warm conditions (60˚F and higher).

 

Gallons of UAN

 

Gallons of Water

N Application Rate

Total solution volume

Lb N/a

Gallons/acre

 

28% UAN

13.4

None

40

13.4

16.8

4.2

50

21

20.1

4.9

60

25

23.5

5.5

70

29

26.8

6.2

80

33

 

30% UAN

12.3

None

40

12.3

15.4

4.6

50

20

18.5

5.5

60

24

21.6

6.4

70

28

24.6

7.4

80

32

 

32% UAN

11.3

None