Posts Tagged ‘18:23’

Pumpkin Spray Programs

Friday, August 20th, 2010

Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland; keverts@umd.edu

I frequently am asked for a “good” spray program for pumpkins. This is always a difficult program to design because it depends on field history (i.e. has Phytophthora crown rot occurred in the field), production practices (no-till vs. bare ground), and the grower’s philosophy about control (Cadillac treatment program vs. minimal inputs). Keep the following in mind to design a good spray program:

● Know what diseases are the most common on your farm. Previous problems with black rot, Phytophthora blight, anthracnose, scab or other diseases may indicate that these diseases are likely to be problems again.

● Know if downy mildew is present on Delmarva. When downy mildew is present your spray program should include effective downy mildew materials. Downy mildew was confirmed in Wicomico County, MD Aug. 17, 2010 (see below).

● Scout 50 old leaves in your field for powdery mildew lesions. If powdery mildew is present in the field, apply materials that are targeted for it.

● Even after implementing a program, scout your fields frequently and modify your program if new disease problems occur.

● Familiarize yourself with the Commercial Vegetable Production Recommendations section on pumpkins. Many fungicides are available for controlling different diseases.

Quintec is a newly registered powdery mildew fungicide. It has performed very well in my trials. Apply at 6 fl. oz. /A with chlorothalonil and alternate with other powdery mildew materials.

Downy mildew has been confirmed in Wicomico County, Maryland. Fungicide spray programs should be revised to include fungicides with good efficacy on downy mildew.

Sprays should be applied on a 7-day schedule. The most effective materials are Ranman, Presidio and Previcur Flex. Tank-mix with a protectant such as chlorothalonil–1.5-3 pt 6F/A and alternate between different modes of action (FRAC codes):

Ranman–2.1-2.75 fl. oz 400 SC/A, plus an adjuvant
or
Presidio–3.0-4.0 fl oz 4SC/A
or
Previcur Flex–1.2 pt 6F/A

Other materials for use in tank mix or alternation:
Tanos–8.0 oz 50WDG/A
or
Curzate–3.2 oz 60DF/A

Materials with different modes of action (FRAC codes) should always be alternated to reduce the chances for fungicide resistance development.

A good fungicide spray program will increase yields and improve quality. The single best way to improve handle quality is to control foliar and fruit diseases in season.

Scout Lima Beans for Disease

Friday, August 20th, 2010

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

At this time last year downy mildew on lima beans had been seen. So far weather conditions have not been favorable for downy mildew. It looks like the weather may be changing and getting a bit cooler with more dew and possibly fog in the early morning hours. If it should start raining soon growers and crop consultants should be scouting for downy mildew. Race F of Phythophthora phaseoli was the only race identified in 2006, 2008 and 2009.

Preventative applications of 2 lbs fixed copper, 2 lbs Ridomil Gold/Copper, or 3- 4 pts Phostrol have provided control of downy mildew in the past. The newest formulation of fixed copper from DuPont is Kocide 3000 and it performs as well as the other formulations of copper at the rate of 1.3 lbs/A. The best controls continue to be Ridomil/Gold Copper, Phostrol or other labeled phosphonate fungicides, especially when disease pressure is high. Application at flowering or when pods are first forming is recommended if weather is favorable for disease. If disease is present Ridomil/Gold Copper and Phostrol have shown to provide some curative activity if applied when downy mildew is first seen. If downy is present in the field do not use copper fungicides alone for curative control, they will not provide control. Another product that is labeled on lima beans for white mold control is Omega but not downy mildew, but in DE this would be a 2ee use that someone like myself can recommend since the fungicide is labeled on lima beans. I have two years data that show excellent control of downy mildew at 5.5 fl oz and 8.0 fl oz/A as a preventative application (before disease is found in the field). Ridomil Gold/Copper has a national label now so no 24c label is needed. Headline from BASF is also labeled for downy mildew as well. I have tested it and it has provided good control of downy when applied on a 10 day schedule at 6.0 fl oz /A. It does not give as good disease control as Ridomil Gold/Copper or Phostrol preventatively but the yields have been comparable. It is also labeled for anthracnose which the other products do not control.

Downy mildew caused by Phytophthora phaseoli

Downy mildew on raceme and petiole

Phytophthora capsici on lima bean pod.

Phytophthora capsici will infect lima bean pods as well and can look very similar. P. capsici or lima bean pod rot is usually found in wet low spots in the field. The fungus growth looks more granulated or “pebbly” than downy mildew, microscopic confirmation is encouraged.

Downy mildew on the upper pod and lima bean pod rot on the lower pod. Note the granular appearance of the fungus on the lower pod and the lack of a reddish brown border on the pod infected with lima bean pod rot or Phytophthora capsici.

Watch for Tomato Late Blight

Friday, August 20th, 2010

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

Late blight has not made an appearance in Delaware so far this year. Late summer and fall is when we usually see it on home garden and truck crop tomatoes. For late tomatoes continue with Bravo and/or mancozeb as your protectant fungicide and add a late blight specific fungicide if late blight should occur in the region. See the 2010 Delaware Commercial Vegetable Production Recommendations for products and rates.

Cucurbit Downy Mildew Update – August 20, 2010

Friday, August 20th, 2010

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

The forecast for downy continues to be moderate to low for most of Delaware and the eastern shore. Maintain fungicide programs to protect cucurbits from infection by downy mildew. This time of year it begins to move to pumpkin, winter and summer squash, cantaloupe and watermelon. For more information on the forecast see the website http://cdm.ipmpipe.org.

Late Summer and Early Fall Consideration for Vegetable Growers

Friday, August 20th, 2010

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

While there will still be hot days ahead, late summer and early fall bring different challenges and opportunities for vegetable growers. The following are some considerations at this time of year:

● The day length is getting shorter each day and there is less heat accumulated during the day. We have passed the latest planting dates for most summer planted – fall harvested crops to go to successful harvest. A good example is with cucumbers where a 2-3 day planting difference in early August (between August 7 and August 10 for example) will mean the difference between a successful crop and a crop that will not mature in time or that will have low yields. Remember that you are up against the first frosts with many of these crops. There is still time however for many of our frost tolerant crops. Greens, earlier maturing broccoli, spinach, and lettuce for harvest in leaf stage can all be planted through the end of the month for fall harvest.

● Extending harvest seasons is a consideration, especially for smaller growers who sell directly. Floating row covers, low tunnels, and high tunnels are all tools to use for frost protecting sensitive crops (such as a late crop of tomatoes) and for carrying cold season crops into the winter and sometimes over the winter. Older methods such as field storing root crops (think parsnips, turnips, carrots) using mulches for later digging can still be employed.

● Late summer and fall planted overwintering crops will be planted over the next 2 months. This includes plasticulture strawberries, spinach, and garlic. However, there are many other vegetable crops that can be successfully overwintered, especially vegetables in the mustard family and onion family and even some cold hardy legumes.

● Cooler nights and lower duration of high temperatures during the day helps to maintain pod set on snap bean and lima bean crops that will be harvested in September through mid-October. This year has been particularly hard on bean crops maturing in July and August.

● Irrigation management becomes less of a challenge for fall crops because evapotranspiration is reduced. Attention should be paid so as not to over-irrigate as the late season progresses to avoid disease problems.

● Late summer and early autumn brings new challenges in regards to pests. This is the time of the year when we see peaks of many insect pests (such as corn earworm), migratory insect populations that have arrived or will arrive in high numbers, and late season insects in higher numbers. With the lower temperatures and longer nights, dews are heavier, often leading to increased disease pressure and the appearance of late season diseases. Throw in a hurricane or tropical storm during this period it can be a recipe for disaster in some vegetable crops.

● This is also the time of year when growers should be planting cover crops, windbreaks, overwintering biofumigant crops, and overwintering legumes for nitrogen sources where next year’s vegetables will be planted. For a review of these options see the WCU article titled Late Summer and Fall Cover Crops for Vegetable Ground in WCU 17:24. Good rotations are critical for vegetable crop production and planning should start now.

Vegetable Crop Insects – August 20, 2010

Friday, August 20th, 2010

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

The potential for corn earworm and corn borer pressure remains high in fall vegetable crops statewide. Trap catches remain high throughout the state and moths can be found laying eggs in fields so you may need to scout fields at least twice a week as well as check local trap catches (http://ag.udel.edu/extension/IPM/traps/latestblt.html or call the Crop Pest Hotline in state: (800) 345-7544; out of state: (302) 831-8851).

Cabbage
Continue to sample for cabbage looper, diamondback larvae, beet armyworm, fall armyworm and Harlequin bug. Although the pyrethroids will provide control of Harlequin bugs they are not effective on diamondback or beet armyworm in our area. So be sure to scout and select controls options based on the complex of insects present in the field.

Lima Beans
Continue to scout for stink bugs, lygus bugs, beet armyworm and corn eaworm. With the high corn earworm moth catches, moths can be readily found laying eggs in fields. Be sure to sample for corn earworm larvae as soon as pin pods are present. A treatment will be needed if you find one corn earworm larvae per 6 ft-of-row. At this time of year, we have also found soybean loopers in lima bean fields. If soybean loopers become a problem again this year, remember that they are a migratory pest, difficult to control and pyrethroid resistance has been documented in states to our south. The Belt SC federal label was recently expanded to include legume vegetables and soybean looper is on the label. However, it is not included on the DDA’s state registration list as of Aug 17. Materials must be labeled both federally and in-state to be used on a crop. We will let you know when it has received a state label as well or you can check their website ( http://www.kellysolutions.com/de/pesticideindex.htm ). The Lannate LV label lists loopers on the label. Be sure check the label for rates, restrictions (including plant back restrictions) and days from last application to harvest.

Peppers
At this time of year, corn borer, corn earworm, beet armyworm and fall armyworm are all potential problems in peppers. So be sure to select the material that will control the complex of insects present in the field. Be sure to check local moth catches in your area by calling the Crop Pest Hotline (n state: (800) 345-7544; out of state: (302) 831-8851) or our webpage at http://ag.udel.edu/extension/IPM/traps/latestblt.html. We are also starting to see aphid populations increasing, especially in fields where pyrethroids have been used on a weekly basis. Treatments for both of these pests will need to be applied before populations explode.

Snap Beans
With the high trap catches, you will need to consider a treatment for both corn borer and corn earworm. You should also watch for beet armyworms. Sprays are needed at the bud and pin stages on processing beans for worm control. With the diversity of worm pest that may be present in fields, be sure to scout fields and select materials that will control the complex of insects present. For the most recent trap catches in your area and to help decide on the spray interval between the pin stage and harvest for ECB control in processing snap beans, you will need to call the Crop Pest in state: (800) 345-7544; out of state: (302) 831-8851 or check our website http://ag.udel.edu/extension/IPM/traps/latestblt.html and http://ag.udel.edu/extension/IPM/thresh/snapbeanecbthresh.html.

Spinach
As the earliest planted spinach emerges from the ground, be sure to watch for webworms and beet armyworms. Both moths are active at this time and controls need to be applied when worms are small and before they have moved deep into the hearts of the plants. We are seeing an increase beet armyworm populations being found in vegetable crops – so it will also be important to select a material that will provide beet armyworm control. As a reminder, the pyrethroids have not provided effective beet armyworm control in past years. It also appears that webworm populations may be heavier than normal (typical during hot, dry seasons) so it is important to apply controls before any webbing occurs. Remember that both insects can produce webbing on the plants. Generally, at least 2 applications are needed to achieve control of webworms and beet armyworm.

Sweet Corn
With the continued high corn earworm trap catches, be sure that a spray is applied as soon as ear shanks are visible on plants. If fall armyworms are present in the whorl, you will need multiple whorl sprays for this insect before the ear shank spray to achieve effective control and to prevent larvae from dropping into the ear zone. Once fields are silking, you will need to check both blacklight and pheromone trap catches for silk spray schedules since the spray schedules can quickly change. (http://ag.udel.edu/extension/IPM/traps/latestblt.html or call the Crop Pest Hotline in state: (800) 345-7544; out of state: (302) 831-8851). Be sure to check all labels for days to harvest and maximum amount allowed per acre.

Twilight Tour With Bees

Friday, August 6th, 2010

Twilight Tour with Bees
Delaware bees, crop pollination, and conservation
Monday, August 30, 2010     5:30 – 7:30 p.m.
Lister Acres (Hurd Family)
5417 Milford-Harrington Highway
Harrington, DE 19952

● Farm Tour: strawberries, melons, flower buffer strips, Heather Harmon Disque, Gordon Johnson, Emmalea Ernest, Bonnie MacCulloch

● Honey Bees: Dr. Debby Delaney, Bob Mitchell

●  Pesticide Safety: Joanne Whalen and Bill Cissel

● Practicality of conservation practices and making changes, Chuck Hurd

RSVP by August 25 to:
Plant Industries
Delaware Department of Ag
Dover, DE 19901
Phone: 302-698-4577
E-mail:
geri.mcclimens@state.de.us

Presented by the Delaware Department of Agriculture and University of Delaware