Cucurbit Anthracnose is a destructive disease affecting cucurbits or vine crops during warm seasons with frequent rains. This article provides an overview of the disease, including its causes, symptoms, and management strategies.
Causes of Cucurbit Anthracnose
The disease is caused by the fungus Colletotrichum spp. It is a worldwide problem that can have devastating effects on cucurbit plants.
Symptoms of Cucurbit Anthracnose
The most noticeable symptoms of Cucurbit Anthracnose appear on the fruit. Young fruits become black, shriveled, and may die if the fruit pedicels are infected. Circular, water-soaked spots develop on older fruits, which gradually turn dark green to black with flesh-colored, oozing centers. Additionally, the disease can affect aboveground plant parts, causing distorted leaves, severe spotting, blighting, and defoliation. Infected fruit may develop brown to black, sunken, water-soaked spots, with the formation of tiny black fruiting structures called acervuli.
Cucurbit Anthracnose Cycle
The Colletotrichum fungus can overwinter in the remains of previous vine crops or in weeds of the cucurbit family. It may also be seed-borne and transmitted by cucumber beetles. The spread and infection of spores rely on water. Contaminated wash water used during the cleaning of cucumbers or melons after harvest can contribute to the spread. Spores can also be carried by cultivating equipment, workers, or cucumber beetles, leading to the contamination of plants within a field or across neighboring fields.
Infection and Environmental Requirements
Direct penetration of plant tissue by the fungus does not require natural openings or wounds. Initial infection typically occurs under high humidity conditions (up to 100% relative humidity) for 24 hours and at temperatures ranging from 20 to 25 °C. Symptoms may appear within 6 days after infection. The fungus can survive for up to two years without a suitable host, but disease development requires warm, humid, and rainy weather at frequent intervals.
Management of Cucurbit Anthracnose
Chemical Control: Fungicides can be used to prevent and eradicate anthracnose disease in cucurbits. Some recommended fungicides include RANSOM 600WP, DUCASSE 250 EW, ABSOLUTE 325 SC, DOMAIN 250 EC, BRADLEY 500SC, EXPLORER 3SL, GREENCOP 500WP, MEGAPRODE LOCK 525WP, JUPITER 125SC, MILLIONAIRE 690WDG, RIMETA GOLD 300SC, and PROVIDENCE 400WP. Fungicides should be reapplied after 1 to 2 weeks for effective control.
Non-chemical Control: Several non-chemical methods can be employed to manage Cucurbit Anthracnose. These include the removal and destruction of infected plants or plant parts (without composting), planting resistant varieties, using certified disease-free or healthy planting materials, ensuring well-drained soil for planting, avoiding overhead irrigation to prevent foliage wetting, practicing caution when handling wet plants, implementing crop rotation with non-host plants every 2 to 3 years, controlling all weeds (especially wild and volunteer cucurbits), and preventing post-harvest losses by avoiding fruit damage.
To control seed coat infections, seed treatment with BIODISTINCTION XTRA is recommended. When applying fungicides, mixing them with INTEGRA can enhance their efficacy. Alternating different fungicides throughout the season helps prevent the development of resistance. Timely control of the disease is critical to minimize losses attributed to anthracnose infection. Finally, providing plants with proper nutrition can boost their immunity against the disease.
Cucurbit Anthracnose caused by the fungus Colletotrichum spp is a significant threat to cucurbit crops worldwide. Recognizing the symptoms, understanding its cycle, and implementing effective management strategies, both chemical and non-chemical, can help minimize the impact of this destructive disease on cucurbit plants.