Posts Tagged ‘20:8’

Potato Disease Advisory #1 – May 10, 2012

Friday, May 11th, 2012

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu; Phillip Sylvester, Kent Co., Ag Agent; phillip@udel.edu

With my impending retirement only a week away, we were concerned that the Potato Disease Advisory email and FAX may not get done this year and would resume hopefully by my replacement. Phillip Sylvester, our Kent County Ag Agent, has volunteered to keep the late blight advisory part of the report operating for potato growers in our area for this season.

Late blight Advisory
We are using the E-WEATHER SERVICE from SkyBit, Inc as we have in the past. The service determines specific requested weather parameters (temperature, relative humidity and rainfall) based on calculations of data from the nearest National Weather Service stations. This weather data is used in the WISDOM software program for predicting late blight and early blight and making spray recommendations. Our location this year is:

Location: Art and Keith Wicks Farm, Rt 9, Leipsic, Kent County
Greenrow: April 20

Date DSV Total DSV Spray Interval Recommendations
4/20 – 4/30 12 12 None
4/30 – 5/1 8 20 7-days
5/1 – 5-8 15 35 5-days

The threat of late blight from seed infection was moderate since there was late blight in 2011 in the seed producing areas. Be vigilant since we have exceeded 18 DSVs already for 2012. The first late blight fungicide application is recommended once 18 Disease Severity Values (DSVs) accumulate from green row. Green row occurred on approximately April 20 at this location. Please be vigilant and keep a look out for suspect infections on young plants coming from infected seed pieces! Growers opting not to use the forecast system should put the first late blight fungicide application on when the plants are 6 inches tall or plants are touching down the row, and repeat every 7 days. There are numerous fungicides now labeled for late blight control; however, use of mancozeb (Manzate, Penncozeb, or Dithane) or chlorothalonil (Bravo) are still very effective early season protective fungicides to use. See the 2012 Commercial Vegetable Production Recommendations-Delaware for more information on products and rates.

The threshold of 18 DSVs has been exceeded. Thirty-five (35) DSVs have accumulated so far for any potatoes that established green row (approximately 50% emergence) prior to and since April 20. Spraying as soon as possible with a protectant fungicide would be advised if not already on a spray program. The forecast looks like favorable weather for late blight will continue. Scout your fields regularly for symptoms. Late blight was reported in northern North Carolina last week.

Vegetable Crop Insects – May 11, 2012

Friday, May 11th, 2012

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

Leafminers in Vegetable Crops
Each spring, we receive reports of leaf miners attacking spring planted vegetable crops. There are a number of potential species that attack vegetables including the vegetable leafminer, serpentine leaf miner, spinach leafminer and beet leafminer. Leaf miners can be difficult to control and we have limited experience with control strategies in our area. The following links provide information on some of the potentially important species:
http://entnemdept.ufl.edu/creatures/veg/leaf/vegetable_leafminer.htm

http://entnemdept.ufl.edu/creatures/veg/leaf/a_serpentine_leafminer.htm

http://extension.umass.edu/vegetable/insects/leafminer-beet-and-spinach

Cabbage
Continue to scout for diamondback and imported cabbageworm larvae. Economic levels of diamondback larvae can be found. A treatment should be applied when 5% of the plants are infested and before larvae move to the hearts of the plants.

Melons
Continue to scout all melons for aphids, cucumber beetles, and spider mites. Economic levels of aphids can be found in some fields but beneficial insects (lady beetles and parasitized aphids) can also be found and they are starting to help manage populations. As a general guideline, a treatment should be applied for aphids when 20 percent of the plants are infested, with 5 aphids per leaf and before significant leaf curling occurs.

Potatoes
Continue to sample for Colorado potato beetle adults and egg laying. A treatment should be considered for adults when you find 25 beetles per 50 plants and defoliation has reached the 10% level. Once larvae are detected, the threshold is 4 small larvae per plant or 1.5 large larvae per plant. Corn borer moths are being found in BLTs throughout the state; however, flights are still low. A corn borer spray may be needed 3-5 days after an increase in trap catches or when we reach 700-degree days (base 50).

Snap Beans
All seedling stage fields should be scouted for leafhopper and thrips activity. The thrips threshold is 5-6 per leaflet and the leafhopper threshold is 5 per sweep. If both insects are present, the threshold for each should be reduced by 1/3. Be sure to also watch for bean leaf beetle feeding. Damage appears as circular holes in leaves and we have seen significant damage in recent years on the earliest planted fields. As a general guideline, a treatment should be considered if you defoliation exceeds 20% prebloom.

Sweet Corn
Continue to sample for cutworms and flea beetles. As a general guideline, treatments should be applied if you find 3% cut plants or 10% leaf feeding. In order to get an accurate estimate of flea beetle populations, fields should be scouted mid-day when beetles are active. A treatment will be needed if 5% of the plants are infested with beetles. Be sure to also watch for corn borer in the whorls of the earliest planted fields. A treatment should be applied if 15% of the plants are infested.

University of Delaware Small Fruit Twilight

Thursday, April 19th, 2012

Tuesday, May 22, 2012     6:00-8:00 p.m.
Carvel Research and Education Center
16483 County Seat Highway
Georgetown, DE 19947

Participants will have the opportunity to tour experimental plots and hear about current research on June-bearing and day-neutral strawberries, blueberries and blackberries.

Strawberry research includes plasticulture variety trials with USDA selections from the Beltsville breeding program; summer planted and overwintered day neutral varieties; spring 2011 planted, overwintered, and crown thinned day neutral varieties for summer 2012 production; use of shade cloth and reflective mulch for temperature reduction in day neutral strawberries; and root inoculant and mustard seed meal treatments for root health and soil disease management in strawberries.

Blueberry research includes a 2011 planted variety trial with southern highbush selections; a mulching material study; and a planting hole treatment study.

Blackberry plots are concentrated on evaluating primocane bearing fall fruiting varieties from the University of Arkansas breeding program.

Also featured will be insect management programs and emerging insect pests of small fruits (spotted wing Drosophila).   Extension specialists and associates will be on hand to lead the tour and answer questions.

Strawberry tastings and light refreshments served.

To register, contact Karen Adams at (302) 856-2585 ext. 540 or email adams@udel.edu

For additional program information, contact Gordon Johnson, gcjohn@udel.edu, (302)-856-2585 ext. 590, gcjohn@udel.edu.