Newsletter

The Weekly Schedule Begins on April 1

Issue 1 of the Weekly Crop Update is a sample of the information you will receive each week with a subscription or access via the internet. The newsletter is designed to provide subscribers with the latest information on disease and insect problems as they develop, timely weed control information, crop progress reports, and other topics related to agronomic and vegetable crop production in Delaware. University of Delaware Extension Specialists and Agents provide information for the newsletter.

The weekly issues will begin on April 1, 2005 and continue through September 30th. The Weekly Crop Update is posted on the web, and sent to mail and fax subscribers each Friday. As in past years, the cost of mail or fax subscription is $30. You can subscribe by returning the form at the back of this issue.

Crop Update is also available for free online at the following address:

http://www.rec.udel.edu/TopLevel/Publicat.htm

For those of you who access the newsletter via the internet we offer to send a weekly email reminder which will let you know when the WCU has been posted online and give you a taste of the headlines. If you would like to receive the email reminder or if you experience problems during the season with the online WCU please contact me at Emmalea@udel.edu or (302)-856-7303.

Soybean Rust Update

Approximately 330 people attended Extension-conducted meetings on Asian soybean rust this winter. Growers and fieldpersons have also taken advantage of industry-sponsored meetings and educational materials on the web. We will attempt to keep you updated this season with timely information in the Weekly Crop Update.

Alerts:

Asian soybean rust was found for the first time in 2005 on kudzu near Dade City, FL in Pasco County north of Tampa. Apparently it has overwintered there, but presently is not known to occur elsewhere. The discovery was made Feb. 23 and confirmed a week later. There had been some question as to whether SBR would overwinter in the U.S. this year, because all the areas that had been infected in November and December received killing frost. However, it looks like we have an answer to this question as the disease did infect and overwinter on kudzu in south Florida where frost does not occur, or occurs sporadically. This means that we will probably have to deal with SBR this season.

Delaware just received section 18 approval for the triazole fungicide Domark (tetraconazole) for control of soybean rust. This fungicide from Valent is labeled at the rate of 4-6 fl. oz/A. When the DDA receives the new label we will post links for all the section 18 fungicides on our Extension Plant Diagnostic Lab Site- http://ag.udel.edu/extension/Information/pdc/PDCindex.htm

General Information

Insect Control Update - Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

As we start the 2005 season, remember that pesticide labels are always changing so it is important to read all labels before applying any pesticide. In some cases, the labels you find on line or even in label books may not be the most recent label or may have changed after printing. Therefore, you always need to use the label that is on the pesticide container. Since the label is the law, it is important to always read the label and follow those directions and restrictions before making any applications. If you are applying a pesticide under a special label (including Section 18’s, Special Local Need 24C’s or 2ee) then you must also have those labels with you at the time of application.

As a result, there will always be changes and corrections that did not make it to our recommendation books. The following are comments on revisions/changes/deletions that need to be made to the 2005 Recommendation Books under Insect Management. This is not intended to be the entire list of changes; therefore, you still need to read all labels before applying any pesticide.

Diazinon – After conversations with EPA last fall and again in recent weeks, here is what I have been told regarding diazinon use in 2005.

Seed Treatments for Vegetable and Field Crops: Seed treatments containing diazinon can be used at least through the end of 2005 under the old labels. The new labels, which need to be submitted this month, will no longer have diazinon on the label as a seed treatment. If you have it in your possession, you should be able to use your existing stocks under the old labels. However, I continue to receive new information so we will keep you posted. These changes will apply to all the hopper box formulations including Diazinon 50W.

Under Seed Treatments in the Vegetable and Field Crop Books: Agrox DL and Germate Plus should be deleted under sweet corn and field corn.

A long list of additional diazinon label changes will also occur this month so it will be important to check the new labels.

Vegetables

Vegetable Crop Insect Control - Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

Cucurbits – The following are a few changes you will find in the 2005 Vegetable Recommendation Book as well as some notes on label specifics:

Guthion is no longer labeled.

Actara is no longer labeled.

Vydate L – The label to apply Vydate through the drip is a 2ee label from DuPont and it expires Dec. 31, 2005. It is only labeled for leafminer control and root knot nematode suppression. http://www.cdms.net/ldat/ld264022.pdf

Acramite 24C Label for Aerial Application – At this point, this label only applies to Delaware and Virginia; however, Maryland also plans to submit for this label and should have it in time for the 2005 season. Some changes to the 24C label (already on the Full Section 3 label) include drift language and a 30 day rotational restriction to non-labeled crops. Please read the label for all the specific information. http://www.cdms.net/ldat/ld4TA006.pdf

Platinum — Syngenta just issued a 2ee label which added early season cucumber beetle control for cucurbit vegetables http://www.cdms.net/ldat/ld55K015.pdf

Peppers – The following corrections and clarifications should be noted in the 2005 recommendations:

Orthene 97 on Non-Bell Peppers – The label states that the maximum rate on non-bell peppers is ½ pound (8 oz) per acre per application and a maximum of 1.0 lb per acre/season. This is the aphid rate so European corn borer control is not listed for Non-Bell Peppers. Therefore, under European corn borer control the rates listed are for Bell Peppers only. In addition, under green peach aphid the same maximum rate applies for non-bell peppers.

Avaunt 30WDG for European Corn Borer Control – This label is a 2ee label from Dupont for Bell Peppers only and it expires on Dec 31, 2005. It should be noted that the label also states that “for best results begin applications of Avaunt following two applications of an organo-phosphate insecticide labeled for European corn borer in bell peppers such as acephate (e.g. Orthene).” Avaunt is labeled for beet armyworm and loopers on bell and non-bell peppers.

http://www.cdms.net/ldat/ld4BD016.pdf

Pea Planting and Weed Control Programs – Ed Kee, Extension Vegetable Specialist; kee@udel.edu

Peas were planted as early as February 18, but as we roll into March and catch some dry weather, planting will hit full stride. We planted our early variety trial at the Research & Education Center on Monday, March 7. A late trial will be planted in April.

Early varieties, which tend to have a more determinant growth habit, and also have to cope with colder soil conditions, should be planted at 24 seeds per yard. The seeding rates of later maturing varieties, many of which branch more, can be reduced to 18 to 20 seeds per yard.

The standard herbicide treatment for much of Delmarva’s acreage is the pre-emergence treatment of Dual Magnum 7.64E at 0.5 pints/acre + Pursuit 70DG at 0.75 ounces/acre. Command is sometimes added at 8 ounces per acre to provide additional grass control and to control velvetleaf and other broadleaf weeds. Command will not control pigweed, but Pursuit and Dual do control it, along with many other grasses and broadleaf weeds.

Growers who will double-crop pickles, any cucurbit crops, spinach or other vegetables need to be aware of residual carry-over from Pursuit that could adversely affect a double-cropped vegetable. If those crops will be planted after peas, then the Pursuit should not be used, and a combination of Command and Dual sprayed as a pre-emergence should be used.

If escaped weeds occur, then post-emergence treatments of Basagran for broadleaf weeds can be used. For escaped grasses, Poast or Assure II can be used. These grass materials should not be tank-mixed with Basagran.

Fungicide Updates for Vegetables- Bob Mulrooney, Extension Plant Pathologist, bobmul@udel.edu

There have been some welcome fungicide additions for 2005. More information can be found in the 2005 Commercial Vegetable Production Recommendations E.B. 137. Be sure to check the labels on these products for specific use information. This publication can be obtained from any of the county Extension offices in Newark, Dover, or Georgetown at the Research and Education Center on Rt. 9.

Amistar is now labeled on asparagus to control purple spot caused by Stemphylium and to control Ascochyta blight on peas.

Switch is now labeled to control Alternaria leafspot on crucifers.

Previcur Flex and Pristine are now labeled for control of downy mildew on cucurbits and late blight on tomato.

It was an oversight on our part but Curzate was inadvertently omitted for control of downy mildew on cucurbits and should have been listed.

Acrobat has added control of downy mildew on mustard greens to its label as well as peppers to control Phytophthora blight.

Actigard has received a national label for control of white rust on spinach.

The Endura label now includes control of white mold on potatoes as well.

Headline was labeled after EB 137 went to print and is not listed in the book. It is now labeled for control of many foliage diseases of sweet corn and foliage diseases of legume vegetables including rust, anthracnose, and Alternaria leaf and pod spot. The one legume group that was not labeled was the succulent shelled legumes, which includes lima beans. Hopefully this will be added back to the label before the use season.

Stewart’s Wilt of Sweet Corn- Bob Mulrooney, Extension Plant Pathologist, bobmul@udel.edu

For control of Stewart's wilt, which is vectored by the corn flea beetle, it is important to control the corn flea beetle. Plant resistant varieties and control the beetles early. The following index predicts conditions favorable for overwintering flea beetle populations not the abundance of the bacteria. The prediction has its limitations including the influence of snow cover on survival, but indicates that flea beetles should have had no trouble overwintering this year based on temperature, especially downstate. The question always becomes how much bacteria is available for them to spread. It is hard to know how the temperature fluctuations that we experienced this year also affect overwintering.

Winter Temperature Index For Predicting Stewart’s Wilt in Delaware Sweet Corn, 1995-2005

Average monthly temperatures in ^oF at Georgetown, DE. REC. 1995-2005

	2004-05	2003- 04	2002-03	2001- 02	2000-01	1999-00	1998-99	1997-98	1996-97	1995-96
December	38.9	38.6	36.7	43.2	31.2	40.3	41.3	39.3	42.0	33.5
January	34.9	29.5	28.9	40.0	33.8	33.9	39.5	42.6	35.0	33.5
February	36.7	35.2	33.8	39.9	38.8	39.7	38.7	40.6	41.5	34.7
INDEX	110.5	103.3	99.4	123.1	103.8	113.9	119.5	122.5	118.5	101.7

Average monthly tempertures in ^oF at Newark, DE Experiment Station. 1995-2005.