Disease Control
Damping-Off.
Use a disease-free planting mix. Consideration should be given to using soilless mixes containing microorganisms that suppress damping-off fungi. Use of the following will assist in control:
SoilGard 12G--1-1.5 lb/cu yd of soilless mix.
SoilGard is a naturally occurring soil fungus that is an antagonist to plant pathogenic fungi. Uniformly add SoilGard 12G when soilless mixes are being blended by mechanical devises. After one day of incubation (keep at room temperature), seed or transplants can be added to the treated mix.
Where planting mix is not used, pretreat seedbeds with metam-sodiuin (Vapam HL) at 0.75 quart per 100 square feet.
Bacterial Leaf Spot.
Plant varieties (Boynton Bell, X3R Aladdin, X3R Camelot, X3R Key West, X3R Wizard, Commandant, and Enterprise) that have resistance to all three races of the pathogen that occur in the region. When producing transplants, be sure to use the Clorox seed treatment described under the preceding "Seed Treatment" section. Use disease-free seeds and a 2-year rotation in the seedbed and field. Apply streptomycin (Agri-Mycin 17, Agri-Strep) sprays (1 pound per 100 gallons, 1 1/4 teaspoons per gallon) when first true leaves appear and continue every 4 to 5 days until transplanting. Streptomycin cannot be used on transplants after they are field-planted.
Loss from bacterial spot may be reduced somewhat by maintaining a high level of fertility. Maintaining high fertility levels will stimulate additional leaf formation to replace those lost from bacterial spot infections. However, sufficient restraint must be used to ensure that plants do not become overly vegetative, or fruit set may be severely reduced. Where disease is present or anticipated, do not work in fields when plant surfaces are wet.
Disk field as soon as possible after the growing season. This will hasten breakdown of the crop debris that is harboring the bacteria and minimize overwintering of the bacteria in the field.
Anthracnose Fruit Rot.
Beginning at flowering, alternate
maneb--l.5-3 lb 75DF/A or OLF every 7-10 days with one of the following:
azoxystrobin (Quadris--6.2 - 15.4 oz 2.08F/A or Amistar--2-5 oz 80WDG/A), or
Cabrio--8-12 oz 20EG/a, or
Flint--3-4 fl oz 50WDG/A
Bacterial Soft Rot.
During periods of humid weather, the stem ends of harvested peppers develop this disease and turn brown. Pack peppers dry without washing to minimize this disease. If peppers must be washed, then maintain 25 ppm of chlorine (1 tablespoon of Clorox per 8 gallons of water) in the wash water. Avoid washing peppers with water more than 10°F (6C) cooler than the fruit temperature to prevent movement of bacteria into the stem end of the fruit.
Phytophthora Blight.
Plant loss can be severe with all pepper types. The disease develops in low areas of the field after heavy rains and can spread throughout the entire field during favorable conditions. Planting on a ridge or raised, dome-shaped bed will assist in control by providing better soil drainage. Use disease-free seed and a 3-year rotation with crops other than peppers, cucurbits, eggplants, or tomatoes. In Phytophthora infested fields or fields with low lying areas present, plant the Phytophthora resistant varieties such as Paladin.
For control of the crown rot phase of blight, apply:
mefenoxam -- l pt Ridomil Gold 4E/A or 1 qt Ultra Flourish 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 postplanting directed applications at 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 formula in the "Calibration for Changing from Broadcast to Band Application" section of Calibrating Granular Application Equipment to determine anount 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.
For prevention of the stem and fruit rot phase of blight, apply the following on a 7- to 10-day schedule:
copper, fixed--2 lb 77WP/A or OLF, or
Ridomil Gold Copper--2.5 lb 65WP/A. Make three to four applications at 10- to 14-day intervals. (Only apply Ridomil Gold 4E at planting and 30 days later. The third application of Ridomil Gold 4E cannot be made when Ridomil Gold Copper is applied.)
The folowing materials are labeled for Phytophthora on peppers but there is little information on efficacy in the Mid-Atlantic region. For best results tank mix with a copper containing fungicide.
Forum--6 oz 4.18SC/A, or
Tanos -- 8-10 oz 50W/A
Blossom End Rot.
This physiological disorder is caused by reduced calcium uptake and movement to the fruit when soil moisture is low. To control blossom end rot, maintain proper soil calcium and nutrient balance. Avoid root pruning and damage. The most effective control is to maintain uniform, favorable soil moisture. This is especially important when using raised beds for Phytophthora control, since soil in raised beds dries more quickly than in flat culture.
Sunscald.
To reduce sunscald, select varieties with good foliage cover. Maintain vigorous vegetative growth by following recommended fertilizer (especially nitrogen) program and timely irrigation. Harvest carefully to avoid breaking foliage.
Southern Blight (Sclerotium).
High soil moisture and temperature favor disease development. Long crop rotations with corn and small grains help reduce disease incidence. Additionally, use the following in the transplant water.
Terraclor -- 3 lb 75WP/100 gal of water or OLF and apply 0.5 pint per plant.
Verticillium Wilt.
The verticillium fungus can attack and reproduce on a number of plants (eggplants, peppers, potatoes, and strawberries for example), and can survive in the soil for many years. Therefore provide as long a rotation as possible. DO NOT grow tomato, potato, or eggplant as an alternate crop. DO NOT plant other solanaceous crops, such as eggplants or tomatoes between pepper plantings.
Viruses.
Tobacco mosaic virus (TMV) : TMV is transmitted mechanically. Use resistant varieties to control TMV.
Aphid-transmitted viruses (PVX, CMV, TEV, PVY, and AMV) : These virus diseases of pepper cannot adequately be controlled with insecticide applications, but symptom expression can be delayed through their use. Since aphids transmit the virus, growers may wish to use yellow trap pans containing water to determine when mass flights of winged aphids occur. Repeated applications of a contact aphicide at those times are most beneficial.
Thrips-transmitted virus (Tomato Spotted Wilt Virus, TSWV, and Inipatiens Necrotic Spot Virus, INSV): TSWV can be severe on peppers during both greenhouse production of transplants and during field production of the crop. INSV causes similar symptoms on peppers as TSWV; however, the virus is not as severe and does not limit production to the same extent as TSWV. The virus is spread to peppers by thrips. During transplant production, thrips transmit the virus from infected ornamental plants (flowers). Be sure not to grow any ornamental bedding plants in the same green house as pepper transplants. Monitor greenhouses and scout fields for thrips. Begin an insecticide program once observed. When observed in the field, treat with an insecticide to control thrips and rogue out TSWV-infected plants.
Information provided is intended for consideration by the user, but is not intended to be a recommendation. Production decisions should be based on consideration of many types of information (scientific, experiential, economic, legal, etc.) available to the user.
Where trade names are used no discrimination is intended, and no endorsement by the Cooperative Extension Service is implied.
Dr. Alan A. MacNab, Professor, Plant Pathology
Penn State College of Agricultural Sciences
211 Buckhout Lab, University Park, PA 16802
Updated: Nov, 2005; EMH
Loaded: Nov, 2005; EMH