Vegetable and Fruit Crops Pathology

Phytophthora blight of cucurbits. Phytophthora blight, caused by Phytophthora capsici, of has already been observed in pumpkin, zucchini squash, and cucumber fields in south and central Illinois. The disease is rapidly spreading, causing damping-off and foliar blight in the fields. Phytophthora blight has become one of the most serious threats to production of cucumbit crops, particularly pumpkins in Illinois. The pathogen causes seedling damping-off, foliar blight, and fruit rot. Yield losses to Phytophthora blight could be as high as 100%. The USEPA has approved a specific exemption for the use of Acrobat 5WP for control of Phytophthora diseases of cucurbit crops in Illinois. More information on Phytophthora blight of cucurbits can be found here.

Section 18 Exemption. The USEPA has approved a specific exemption under section 18 of FIFRA for the use of Acrobat 50WP (active ingredient: dimethomorph) for control of Phytophthora blight and fruit rot of cucurbit crops in Illinois. Phytophthora blight and fruit rot, caused by Phytophthora capsici, has become a serious threat to production of cucurbit crops in Illinois. Acrobat 50WP (EPA Reg. No. 241-410), manufactured by BASF Corporation, is a protectant-systemic compound, effective against P. capsici. The specific exemption under section 18 has been requested and approved for the use of Acrobat 50WP for control Phytophthora blight and fruit rot of cantaloupe, cucumber, pumpkin, squash (summer and winter), and watermelon throughout the state. The use of Acrobat 50WP has been approved for the period of May 1, 2002 and November 1, 2002. Acrobat 50WP may be applied by ground or air at a maximum rate of 6.4 ounces pound product (3.2 oz dimethomorph) per acre, a maximum of 5 times per season. A 4-day PHI will be observed.

Anthracnose of cucurbits. Last week, anthracnose was observed in a cucumber field in southern Illinois. Anthracnose, caused by the fungus Colletotrichum orbiculare, is considered to be one of the most destructive diseases of cucurbits in Illinois. The disease generally occurs on cucumbers, melons, and watermelons.

All above ground plant parts can be infected. Leaves first show small, pale-yellow or water-soaked lesions that enlarge rapidly and turn tan to dark brown or black. The lesions may merge blighting large areas of the leaves. The dry, dead centers of the lesions may be torn away by wind-blown rain. Circular, water-soaked spots develop on fruit. Infected young fruit may turn black, shrivel, and die if fruit petioles are infected. Severely infected fruit are bitter to the taste and rot quickly when secondary organisms invade the broken rind.

Anthracnose is readily controlled if the practices outlined below are followed. (1) Plant only certified pathogen-free seed. (2) Rotate cucurbit crops with non-cucurbit crops for three years. (3) Avoid working in the field when plants are wet. (4 Where possible, collect and burn or plow down infected plant debris after harvest. (5 Where possible, grow watermelon and cucumber varieties with resistance to common races of the pathogen. (7) Follow rigorous, weekly spray program starting at first true leaf stage. Thorough coverage of all foliage with spray is essential. For more information on controlling anthracnose of cucurbits, consult "Midwest Vegetable production Guide for commercial Growers."

More information regarding anthracnose of cucurbits can be found here.

Phytophthora blight of pepper. Phytophthora blight of pepper, caused by Phytophthora capsici, has already been observed in commercial fields in southern Illinois. This disease is the most serious diseases of peppers in Illinois. P. capsici can infect the host plant at any growth stage and causes root rot, crown rot, foliar blight, and fruit rot. The disease is more common from mid to late season and is associated with high temperatures and heavy rainfall or excessive irrigation. Control of P. capsici in the field is difficult. The most effective method for control of this disease is planting resistant varieties. Emerald Isle, Paladin, and Reinger have been found resistant to P. capsici in Illinois.

July 5th
	Vegetable Diseases Updates:
	Phytophthora blight of cucurbits. Phytophthora blight, caused by Phytophthora capsici, of has already been observed in pumpkin, zucchini squash, and cucumber fields in south and central Illinois. The disease is rapidly spreading, causing damping-off and foliar blight in the fields. Phytophthora blight has become one of the most serious threats to production of cucumbit crops, particularly pumpkins in Illinois. The pathogen causes seedling damping-off, foliar blight, and fruit rot. Yield losses to Phytophthora blight could be as high as 100%. The USEPA has approved a specific exemption for the use of Acrobat 5WP for control of Phytophthora diseases of cucurbit crops in Illinois. More information on Phytophthora blight of cucurbits can be found here. Section 18 Exemption. The USEPA has approved a specific exemption under section 18 of FIFRA for the use of Acrobat 50WP (active ingredient: dimethomorph) for control of Phytophthora blight and fruit rot of cucurbit crops in Illinois. Phytophthora blight and fruit rot, caused by Phytophthora capsici, has become a serious threat to production of cucurbit crops in Illinois. Acrobat 50WP (EPA Reg. No. 241-410), manufactured by BASF Corporation, is a protectant-systemic compound, effective against P. capsici. The specific exemption under section 18 has been requested and approved for the use of Acrobat 50WP for control Phytophthora blight and fruit rot of cantaloupe, cucumber, pumpkin, squash (summer and winter), and watermelon throughout the state. The use of Acrobat 50WP has been approved for the period of May 1, 2002 and November 1, 2002. Acrobat 50WP may be applied by ground or air at a maximum rate of 6.4 ounces pound product (3.2 oz dimethomorph) per acre, a maximum of 5 times per season. A 4-day PHI will be observed. Anthracnose of cucurbits. Last week, anthracnose was observed in a cucumber field in southern Illinois. Anthracnose, caused by the fungus Colletotrichum orbiculare, is considered to be one of the most destructive diseases of cucurbits in Illinois. The disease generally occurs on cucumbers, melons, and watermelons. All above ground plant parts can be infected. Leaves first show small, pale-yellow or water-soaked lesions that enlarge rapidly and turn tan to dark brown or black. The lesions may merge blighting large areas of the leaves. The dry, dead centers of the lesions may be torn away by wind-blown rain. Circular, water-soaked spots develop on fruit. Infected young fruit may turn black, shrivel, and die if fruit petioles are infected. Severely infected fruit are bitter to the taste and rot quickly when secondary organisms invade the broken rind. Anthracnose is readily controlled if the practices outlined below are followed. (1) Plant only certified pathogen-free seed. (2) Rotate cucurbit crops with non-cucurbit crops for three years. (3) Avoid working in the field when plants are wet. (4 Where possible, collect and burn or plow down infected plant debris after harvest. (5 Where possible, grow watermelon and cucumber varieties with resistance to common races of the pathogen. (7) Follow rigorous, weekly spray program starting at first true leaf stage. Thorough coverage of all foliage with spray is essential. For more information on controlling anthracnose of cucurbits, consult "Midwest Vegetable production Guide for commercial Growers." More information regarding anthracnose of cucurbits can be found *here. Phytophthora blight of pepper*. Phytophthora blight of pepper, caused by Phytophthora capsici, has already been observed in commercial fields in southern Illinois. This disease is the most serious diseases of peppers in Illinois. P. capsici can infect the host plant at any growth stage and causes root rot, crown rot, foliar blight, and fruit rot. The disease is more common from mid to late season and is associated with high temperatures and heavy rainfall or excessive irrigation. Control of P. capsici in the field is difficult. The most effective method for control of this disease is planting resistant varieties. Emerald Isle, Paladin, and Reinger have been found resistant to P. capsici in Illinois.