Volume 8, Issue 12                                                                                                                       June 9, 2000

 

Vegetables

 

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

 

Peppers.

Corn borer controls are needed on all plantings where fruit is ½ -inch in size or larger and corn borer catches are above 2–5 per night in local blacklight traps. If Orthene or Address (both acepahte) are used, the new 2000 labels state that you can not use more than 2 2/3 lb per acre per crop cycle. If you have material available with the old label, it can still be used under the old label restrictions. Since corn borers are a significant problem on peppers grown in our region, we are also investigating the possibility of a regional Special Local Needs label (Section 24C) to increase the number of applications for the region. Since the recommended corn borer rate is 1 1/3 lb per acre, this limits the number of applications to two under the new label. You will then need to switch to Ambush, Baythroid, Lannate, Pounce or Spintor. You will need to combine dimethoate with the previous products for pepper maggot control.  As aphid populations increase later in the season, be sure to avoid continuous use of pyrethroids which have been known to flare aphid populations. Remember, you can call the Crop Pest Hotline: 1-800-345-7544 instate only or 1-302-831- 8851 or check our website  (http://www.udel.edu/IPM/latestblt.html) for the most recent corn borer catches in your area.

 

Potatoes.

Continue to sample fields for CPB, corn borer, leafhoppers and aphids. At this time, first generation corn borer moth flights have peaked. If a pyrethroid, Penncap or Spintor are used for corn borer control and trap catches remain above 10 per night in local traps, sprays may be needed through June. If Furadan or Monitor is used, you can still sample for infested terminals and treat if you find 25% infested terminals. Potato leafhopper populations continue to increase and nymphs can now be found. Nymphs can quickly cause damage which seems to appear overnight. The treatment threshold is 5-10 leafhoppers per 10 sweeps and/or 1 nymph per every 10 leaves. Provado, a pyrethoid, or Furadan will provide control. Aphid populations are still low in most fields. From bloom until 2 weeks from harvest, the treatment threshold is 4 per leaf. If melon aphids are found, the threshold should be reduced by one-half.

 

Snap Beans.

Fresh market and processing snap beans should be sprayed for corn borer in areas where corn borer trap catches range from 2 to 5 per night. An Orthene or Address (both acepahte) should be used at the bud and pin stages on processing beans. Once pins are present on fresh market snap beans, a 7-day schedule should be maintained for corn borer. Lannate, Asana or Capture are labeled. Capture has a 9-day REI (restricted re-entry interval) in fresh market snap beans.

 

Sweet Corn.

In most areas of the state, fresh market silking sweet corn should be sprayed on a 3-4 day silk spray schedule. One exception is the Milford area where trap catches of corn earworms exceeded 30 per night. Silk sprays in the Milford area should be applied on a 2-day schedule. Trap catches can be found at http://www.udel.edu/IPM/latestblt.html.

 

 

 

Late Blight Update - - Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

 

Disease Severity Value (DSV) Accumulations as of June 4, 2000 are as follows:

Remember that 18 DSV’s is the threshold to begin a spray program

 

Emergence

Date

DSV’s

June 

4

DSV’s

June

7

Recommendation

April 14

93

99

7-day, low rate

April 21

66

72

7-day, low rate

April 27

51

57

7-day, low rate

May 20

33

39

7-day, low rate

May 24

6

12

No Spray

 

 Accumulated 0 DSV’s since the last report.

 

All potatoes that have reached greenrow before May 20 need to be protected with fungicide.

 

Although the predictor is calling for low rates, I would suggest a medium rate for potatoes that are approaching bloom.

Reminder for pink rot control to apply Ridomil Gold MZ for Flouranil when tubers are nickel-size and repeat 14 days later.

 

 


 

Vegetable Diseases -  Kate Everts, Extension Vegetable Pathologist, University of Delaware and University of Maryland;  everts@udel.edu

Melcast for Watermelons

EFI Values (Environmental Favorability Index)

Do not use MELCAST if there is a disease outbreak in your field, it is a preventative program.  Any questions please call Phil Shields at (410) 742-8788 or e-mail: ps136@umail.umd.edu

 

Location

5/31

6/1

6/2

6/3

6/4

6/5

6/6

6/7

Bridgeville, DE

 

0

4

3

0

0

2

0

Laurel, DE

(Collins Farms)

 

0

3

3

0

0

2

0

Galestown, MD

 

0

3

3

0

0

2

0

Georgetown, DE

0

1

4

3

0

0

 

 

Hebron, MD

 

0

4

3

0

0

2

0

Salisbury, MD

0

0

4

3

0

0

2

0

Vienna, MD

 

1

4

3

0

0

2

0

Laurel, DE

(Vincent Farms)

 

0

3

3

0

0

2

1

Watermelon Fields should be sprayed with a fungicide when 30 EFI values have been accumulated by the weather station nearest your fields.  Add 2 points for every overhead irrigation.  After a fungicide spray, reset your counter to 0 and start over.  If a spray has NOT been applied in 14 days, apply a fungicide and reset the counter to zero.  The first and last day above can be partial days so use the larger EFI value of this report and other reports for any specific day

More detailed information concerning MELCAST and sample data sheets are available on the web at http://www.agnr.umd.edu/users/vegdisease/vegdisease.htm or http://www.udel.edu/IPM/. .     v


 

Field Crops

 

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

 

Alfalfa.

Here is some additional information on the affect of alfalfa weevil damage on plant regrowth. It is provided by Les Vough, Extension Forage Crops Specialist at the University of Maryland. Last week we discussed extending the cutting schedule to 35 – 38 days in damaged fields.  Keep in mind that we are talking about 35 to 38 days from the time regrowth has begun.  It may have already been 2 to 3 weeks since cutting and regrowth is just now beginning, so that means 35 to 38 days from now.  Rather than basing it on days, growers should let the second cutting go to about 25% bloom. With the predicted summer drought and current stressed conditions of damaged plants, some extra recovery time will be beneficial. An adequate fall recovery period will be more critical this year because of this damage. Les recommends 55- to 60-day recovery period prior to the fall cutting, i.e. last summer cutting completed by August 20 to 25 (August 10 to 15 in mountain  areas of western Maryland) and harvest around October 20.  So adjust 2nd cutting harvest date as much as possible to achieve the desired time period for 3rd cutting. Second cutting will have reduced stem numbers/plant and most likely

significantly reduced yield.  We don't expect stand loss of good, vigorous stands.  New late summer seedings and older, week stands could possibly be affected. As indicated in last week’s newsletter, monitoring for potato leafhopper will be especially important in these fields.

 

Field Corn.

Although economic levels of cereal leaf beetle in small grains were scattered throughout the state, we are starting to see cereal leaf beetle feeding on field corn. Damage can appear significant; however, it is usually confined to field edges near wheat fields and generally plants outgrow the damage. No treatments will be needed unless you find 10 or more beetles per plant and 50% of the plants exhibit feeding damage. In some cases, an edge treatment may be needed. A pyrethoid will provide control. You should also begin scouting the earliest planted non-Bt corn for the presence of European corn and southern corn stalk borers. Since we rarely treat for the southern corn stalk borer, be sure to pull out the whorls of 10-20 plants per field to determine which insect is causing the damage. Southern corn stalk borer larvae will appear spotted compared to the cream colored body of the corn borer. In addition, small corn borers can be killed by a number of natural factors so be sure you find live larvae before making a treatment decision. We are seeing plants with damage but larvae are no longer present in irrigated corn, a corn borer treatment should be considered if 50% of the whorls are infested with live larvae. In non-irrigated corn, the treatment threshold is 75-80% infested plants. Ambush, Pounce, or Warrior will provide the best control.

 

Small Grains.

We have started to notice wheat fields with bleached heads. Although this may be attributed to a number of factors do not forget that Hessian fly can cause similar damage. In early planted wheat with bleached heads,  we can also find the “flax seed” stage (Hessian fly puparium) present at the upper stem joints. As wheat dries down, this feeding damage will weaken the stems and you could see lodged stems in the next 10 day to 2 week period.

 

Timothy.

We have positively identified a rust mite which attacks timothy.  Field will appear yellow and stunted with the plants and leaves tightly rolled described by some as “ pineapple-like ”. In general, this mite causes most of its damage when the weather is cooler. In the summer, the mites appear to become inactive. This rust mite has caused significant problems in Western Maryland for the past few years and was also detected in Pennsylvania this season. Control has been very difficult since the mites can move deep into the curled leaves.  In addition, labeled insecticides/miticides are very limited. Work done at the University of Maryland has demonstrated that Sevin has provided effective control. They are pursuing a Special Local Needs label (24C). We will pursue a similar label and keep you informed of the progress.

 

Soybeans.

The first spider mites have been detected in soybeans in Sussex County and on the Eastern Shore of Maryland. Mites have been present in watermelon fields since early May. Since mites “balloon” between fields, it will be important to check the entire field, not just field edges. No treatment will be needed until you find 20-30 mites per leaflet or 10 % of the plants are showing stippling damage at the base of leaves on at least 1/3 of the plants. Here is some additional information from Deadline MPs and Bullets for slug control in soybeans: (1) They have had good control with the MP formulation if with 3-inches of rain after application,  (2) 10 lbs per acre of Deadline MPs has worked well – get good distribution in the field, (3) If you use the Bullet formulation, you will need to use 15 – 25 lbs to get the same coverage and control.  

 

 

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

 

Use Options With Caution

Record open interest in corn options signals many things, among them, grain traders are putting on option positions ahead of expected volatile commodity prices this summer. It may also signal that grain traders are looking for ways, any way, to garner a few extra cents per bushel from this year's crop. This is a good time for a cautionary update.

 

Options can be used as a tool to limit price risk. The purchase of put options can be used to establish a minimum price for the commodity to be sold. On June 2, 2000 the premium for a $3.00 Dec corn put was 60 cents per bushel. That equates to a guaranteed minimum price of  $2.60 per bushel (Strike Price - Premium (+or-) Basis = Minimum Price), $3.00 - .60 + .20 = $2.60 (assuming one were to lock in the basis simultaneously on a basis contract). The government loan rate guarantees a minimum price of $2.10 per bushel, locally and $1.90 per bushel in the midwest. Generally speaking a corn option costing over 20 cents per bushel is considered overly expensive. As a point of interest, for a Midwestern farmer purchasing this same put option the guaranteed minimum price is only $2.10 per bushel (assuming basis at 30 under). Yet, when one considers the size of the premium at 60 cents per bushel, the purchaser of said option would be risking $3,000 plus commission on every 5,000 bushel contract. Purchasing puts for price protection is a subject we are likely to revisit as the summer weather market progresses. Remember, when purchasing options price risk is limited.

 

There is another 'speculative' side to options strategies, and many of them are being hyped this year. The problem is that they actually increase the grain seller's price risk. It is important to remember, "When buying options the most money that can be lost is the premium paid. Conversely, when selling (writing) options, the most money that can be made is the premium". The price risk is unlimited. In a worst case scenario, the futures market rallies during a weather market, the option seller writes big check(s) to margin the account which is exercised into a short futures position once the underlying future exceeds the strike price. The most important thing to remember is to get all of the facts straight before employing any speculative options and/or futures strategies. Most of the time the use of speculative strategies will not pay, based on the fact that 90% of all commodity speculative positions loose money.

 

 

Two That Did Not Get Mentioned Last Week - Mark VanGessel, Extension Weed Specialist; mjv@udel.edu  

Last week I wrote about herbicides for use in corn to control emerged grassy weeds.  I forgot to mention Basis and atrazine.  Basis will control emerged foxtails and fall panicum and atrazine will control emerged foxtails (but not fall panicum).  Basis will provide some control of small crabgrass (less than 2 leaves).  Basis must be applied to young corn plants (2 visible collars or less 5 visible leaves).  Do not apply Basis to corn previously treated with Counter 15G. Applications to corn previously treated with Counter 20CR or Thimet may cause unacceptable crop injury, especially on soils of less than 4% organic matter; applications to corn previously treated with Dyfonate, Lorsban, or other organophosphate insecticides may result in temporary crop injury.

 

The key to effective postemergence grass control in corn at lowest possible cost is to spray early and be sure of the weed species you are trying to control.

 

Height Restrictions On Corn Herbicides  - Mark VanGessel, Extension Weed Specialist; mjv@udel.edu  

Below is the maximum corn size for over the top application of the respective herbicide.

 

Accent                         up to 20" or less than 6 collars

Aim                              up to 8 collars

Atrazine                        up to 12"

Banvel/Clarity               up to 36" at ½ pt/A

Basis                            6" or 4 leaves

Basis Gold                    up to 12"

Beacon                         up to 20" or 6 collars max

Bladex                          up to 4 leaves

Celebrity                      up to 20" or less than 6 collars

Distinct                         4 to 10" at 6 oz rate and up to 24" at 4 oz/A

Exceed                         4 to 20" or 6 collars max

Hornet              up to 20"

Liberty                         up to 24" or 7 collars max

Marksman                    up to 8" or 5 leaf stage

Permit                          up to 48"

Resource                      2 to 10 leaf stage

Roundup Ultra              up to 30" or 8 collars max

2,4-D                           less than 8"

 

Recent Registration of Distinct Herbicide  - Mark VanGessel, Extension Weed Specialist; mjv@udel.edu  

BASF recently received registration of Distinct for postemergence control of broadleaf weeds in corn.  Distinct is a combination of dicamba (sodium salt) and another plant growth regulator herbicide (diflufenzopyr).  Dicamba is the active ingredient in Banvel and Clarity.  While the sodium salt results in different environmental characteristics of the dicamba molecule (i.e. volatility, temperature), there needs to be caution in how it is used.  The dicamba amount at the 6 oz rate of Distinct is the same as 6 fluid ounces of Banvel.  The 4 oz rate of Distinct is comparable to 4 fluid ounces of Banvel.  So read the label concerning cautions with Distinct use.

 

UpComing Events…

Processing Pea Variety Trial Twilight Meeting

Date:    June 14, 2000

Time:    5:00 p.m.

Location:          U of D Research & Education Center, Dill Farm

For Further Information: Contact Ed Kee at 302-856-7303

 

Vegetable Pest Scouting Twilight Meeting

Date:    June 20, 2000

Time:    6:00 p.m.

Location:          Vince Winkler’s Farm, Kent County

For Further Information: Contact Gordon Johnson at 302-697-4000.

 

Weather Summary

 

Week of June 1 to June 7

Rainfall:

0.10 inches: June 2, 2000

0.80 inches June 6, 2000

Readings taken for the previous 24 hours at 8 a.m.

Air Temperature:

Highs Ranged from 92°F on June 2 to 62° F on June 6.

Lows Ranged from 66°F on June 2 to 52° F on June 4.

Soil Temperature:

74°F average for the week.

(Soil temperature taken at a 2 inch depth, under sod)

Web Address for the U of D Research & Education Center:

http://www.rec.udel.edu

 

Compiled and Edited By:

Tracy Wootten

Extension Associate - Vegetable Crops

 

Cooperative Extension Education in Agriculture and home Economics, University of Delaware, Delaware State College and the United States Department of Agriculture cooperating, John C. Nye, Dean and Director.  Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914.  Is the policy of the Delaware Cooperative Extension System that no person shall be subjected to discrimination on the grounds of race, sex, disability, age or national origin.

 

 

 

 

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