Posts Tagged ‘pepper phytophthora blight’

Early Season Pythium and Phytophthora Control in Pepper and Tomato Crops

Thursday, April 19th, 2012

Andy Wyenandt, Specialist in Vegetable Pathology, Rutgers University; wyenandt@aesop.rutgers.edu

With the dry spring we’ve had thus far, it’s easy to forget about Pythium and Phytophthora! The same question always comes up about this time of year when growers begin to start thinking about transplanting their tomato and pepper crops. “What should I do to help prevent Pythium and Phytophthora?”. In years past, the answer was simple, apply mefenoxam (Ridomil Gold SL, Ultra Flourish, 4) or metalaxyl (MetaStar, 4). Problem solved, right? In the past, that answer was right, but with resistance development in Phytophthora (P. capsici) to both mefenoxam and metalaxyl, the correct answer isn’t so simple anymore. It’s important to remember that both chemistries will work very well as long as resistance hasn’t been detected on your farm.

How do you know if you have resistance? The easiest way is to follow efficacy. If the chemistries no longer provide the control they once did, then there is a good chance you have mefenoxam-insensitive Phytophthora populations present on your farm. There are also lab services which test for resistance. Remember, once resistance develops it can linger around for a very long time. Therefore, proper crop rotation and resistance management is critical before resistance has the chance to develop.

Our options for pre-transplant applications include a Ranman (cyazofamid, 21) drench one week before transplanting for Pythium in tomatoes as well as Previcur Flex (propamocarb HCL, 28) for the suppression of Pythium and Phytopthora in tomatoes and peppers. Phosphite fungicides, such as ProPhyt and K-Phite (FRAC code 33) can also be applied as a pre-transplant drench in the greenhouse. Additionally, there are a number of biologicals such as Trichoderma, Streptomyces, and Bacillus products which can also be used in the greenhouse to help suppress soil-borne pathogens. Remember, the biologicals need to be applied without conventional fungicides.

At transplanting applications now include Ranman (cyazofamid, 21) in the transplant water or through drip irrigation for Pythium control. There is a section 2ee for the use of Previcur Flex (propamocarb HCL, 28) + Admire Pro (imidacloprid) in transplanting water for Pythium control. Presidio (fluopicolide, 43) now has a label for drip application for Phytophthora control when conditions are favorable for disease development. Additionally, phosphite fungicides, Pro-Phyt and K-Phite (FRAC code 33) can also be applied through drip irrigation at transplanting to help suppress Phytophthora blight. Unlike in the past, there are a number of good options for early season control of these pathogens, it just takes a little bit more planning ahead of time. For further details on use and crop labeled please refer to the specific fungicide label. Remember the label is the law.

Pepper Phytophthora Blight Control Recommendations

Friday, May 6th, 2011

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

For control of the crown rot phase of phytophthora blight in pepper:
Apply 1.0 pt Ridomil Gold 4SL/A or 1.0 qt Ultra Flourish 2E/A (mefenoxam, 4), or MetaStar (metalaxyl, 4) at 4.0 to 8.0 pt 2E/A. Apply broadcast prior to planting or in a 12- to 16-inch band over the row before or after transplanting. Make two additional post planting directed applications with 1 pint Ridomil Gold SL or 1 qt Ultra Flourish 2E per acre to 6 to 10 inches of soil on either side of the plants at 30-day intervals. Use formula titled “Calibration for Changing from Broadcast to Band Application” from Calibrating Granular Application Equipment in Section E of the Delaware Commercial Vegetable Production Recommendations to determine the amount of Ridomil Gold needed per acre when band applications are made. When using polyethylene mulch, apply Ridomil Gold 4SL at the above rates and timing by injection through the trickle irrigation system. Dilute Ridomil Gold 4SL prior to injecting to prevent damage to injector pump. Do not use mefenaoxam or metalaxyl if insensitive strains of Phytophthora capsici are present.

 

Pepper Disease Control

Friday, June 26th, 2009

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

Delaware does not have the acres of peppers we once had but it is still an important crop. The following are several disease control suggestions from Andy Wyenandt from Rutgers University that are timely.

Bacterial leaf spot
Bacterial leaf spot has been found. Symptoms of bacterial spot on pepper leaves include small, brown water-soaked lesions that turn brown and necrotic in the centers. Spots may coalesce and form large blighted areas on leaves and premature defoliation can occur. On fruit, brown lesions can form which have a roughened, cracked, wart-like appearance. High temperatures, high relative humidity and rainfall favor bacterial spot development. Losses from bacterial spot can be reduced somewhat by maintaining high levels of fertility, which will stimulate new growth. Applying a fixed copper (M1) at labeled rates plus maneb (M3) at 1.5 lbs 75DF/A or 8.0 to 10.0 oz Tanos (famaxodone + cymoxanil, 11 + 27) may help suppress spread. For more information on control of bacterial leaf spot of pepper please see the Delaware Commercial Vegetable Production Recommendations.

Phytophthora Blight on Pepper
For control of the crown rot phase of blight, broadcast prior to planting or in a 12 to 16-inch band over the row before or after transplanting:
1.0 pt Ridomil Gold 4E/A,
or
1.0 qt Ultra Flourish 2E/A (mefenoxam, 4),
or
MetaStar (metalaxyl, 4) at 4.0 to 8.0 pt 2E/A.

Make two additional post planting directed applications with 1 pint Ridomil Gold 4E or 1 qt Ultra Flourish 2E per acre to 6 to 10 inches of soil on either side of the plants at 30-day intervals. Use the formula “Calibration for Changing from Broadcast to Band Application” on page E6 in the Pest Management Section of the Delaware Commercial Vegetable Production Recommendations to determine amount of Ridomil Gold needed per acre when band applications are made.  When using polyethylene mulch, apply Ridomil Gold 4E at the above rates and timing by injection through the trickle irrigation system. Dilute Ridomil Gold 4E prior to injecting to prevent damage to injector pump.

Anthracnose on Pepper
Symptoms of fruit infection include sunken, circular spots which develop blackish-tan to orange concentric rings as lesions develop. Lesions on stems and leaves appear as grayish brown spots with dark margins and can easily be overlooked. Control of anthracnose begins with scouting on a regular basis and applying preventative fungicide applications before symptoms appear, especially in fields or areas of your farm where you have had anthracnose problems in the past. Beginning at flowering and as small fruit begin to set, alternate maneb (M3) at 1.5 to 3 lb/A 75DF with one of the following FRAC code 11 fungicides:
azoxystrobin (Quadris at 6.0 to 15.5 fl oz 2.08F/A),
or
Flint (trifloxystrobin) 50WDG at 3.0 to 4.0 oz/A,
or
Cabrio (pyraclostrobin) 20EG at 8.0 to 12.0 oz/A,
or
Tanos (famaxodone + cymoxanil, 11 + 27) at 8 to 10 50WDG/A.

After harvesting, pepper fields should be disked and plowed under thoroughly to bury crop debris.

pepperanthracnoseAnthracnose on pepper fruit

Controlling the Crown Rot Phase of Pepper Phytophthora Blight

Friday, May 22nd, 2009

Andy Wyenandt, Assistant Extension Specialist in Vegetable Pathology, Rutgers University; wyenandt@aesop.rutgers.edu

To control the crown rot phase of Phytophthora blight in pepper apply 1.0 pt Ridomil Gold 4E/A or 1.0 qt Ultra Flourish 2E/A (mefenoxam, 4), or MetaStar metalaxyl, (4) at 4.0 to 8.0 pt 2E/A. Apply broadcast prior to planting or in a 12-16 inch band over the row before or after transplanting. Make two additional post planting directed applications with 1 pint/A Ridomil Gold 4E or 1 qt/A Ultra Flourish 2E to 6 to 10 inches of soil on either side of the plants at 30-day intervals. Use the formula “Calibration for Changing from Broadcast to Band Application” on page E6 in the Pest Management Section of the Delaware Commercial Vegetable Production Recommendations to determine amount of Ridomil Gold needed per acre when band applications are made. When using polyethylene mulch, apply Ridomil Gold 4E at the above rates and timing by injection through the trickle irrigation system. Dilute Ridomil Gold 4E prior to injecting to prevent damage to the injector pump.

Vegetable Crop Diseases

Friday, May 16th, 2008

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

Pepper Phytophthora Blight
For control of the crown rot phase of blight: Apply 1 pt Ridomil Gold 4E/A or 1 qt Ultra Flourish 2E/A (mefenoxam, 4). Apply broadcast prior to planting or in a 12 to 16-inch band over the row before or after transplanting. Make two additional post-planting directed applications with 1 pint Ridomil Gold 4E or 1 qt Ultra Flourish 2E per acre to 6 to 10 inches of soil on either side of the plants at 30-day intervals. Use the formula under “Calibration for Changing from Broadcast to Band Application” on page E6 of the 2008 DE Commercial Vegetable Production Recommendations to determine the amount of Ridomil Gold needed per acre when band applications are made. When using polyethylene mulch, apply Ridomil Gold 4E at the above rates and timing by injection through the trickle irrigation system. Dilute Ridomil Gold 4E prior to injecting to prevent damage to injector pump.

Tomato Bacterial Spot and Speck
Both bacterial diseases can cause serious problems in the field if infections begin in the greenhouse prior to transplanting.
Symptoms of spot and speck look very similar on infected leaves. Lesions are small, circular, blackish-brown and, with time, develop a halo or yellowing of tissue surrounding the lesion. As lesions develop they can coalesce (join together) and can cause premature death. Since sources for these diseases include seed, weed hosts, volunteer plants and contaminated wood (benches) make sure production or holding areas are disinfested, weed-free and clean prior to introducing transplants. Inspect all seedlings prior to transplanting. Infections can occur on all parts of the tomato plant and can easily be spread during transplant production, by transplanting with contaminated equipment, and by workers’ hands. Tomato transplants with suspected symptoms can be treated with streptomycin (Agri-Mycin 17, Agri-Strep, 25) at 1 lb/100 gallons, or 1.25 teaspoon per gallon every 4 to 5 days prior to transplanting. Additionally, Kocide 3000 (copper hydroxide, FRAC code M1), the updated formulation from Dupont, has a greenhouse label for speck and spot control in the greenhouse. Apply 0.5 to 1.5 tablespoons per 1000 sq ft every 5 to 10 days. Remember, phytoxicity is an important issue when apply copper in enclosed structures. See label for cautions, restrictions and liabilities. After transplanting, apply Actigard at 0.33 oz 50 WG/A, or fixed copper (M1) at 1 lb a.i./A plus a mancozeb (Dithane, Manex II, Manzate, Penncozeb, M3) at 1.5 lb 75DF or OLF/A, or ManKocide (M1 + M3) at 2.5 to 5.0 lb 61WP/A, or Cuprofix MZ (M1 + M3) at 1.75 to 7.25 lb 52.5DF/A on a 7-day schedule.

From Andy Wyenandt, Rutgers University