Gummy stem blight

Gummy stem blight, caused by the fungus Stagonosporopsis caricae, is a severe fungal disease that impacts a wide range of cucurbit crops worldwide. It is recognized as one of the most destructive diseases in both protected greenhouses and open-field cultivation systems.

The primary hosts of this pathogen include watermelon, cucumber, cantaloupe, pumpkin, and squash. The fungus is highly opportunistic, often exploiting wounds caused by insects, harvesting tools, or environmental stressors such as hail or wind damage to enter the plant tissue.

The hallmark symptoms include brown, necrotic lesions on stems, leaves, and fruits. A diagnostic characteristic of the infection on stems is the exudation of a gummy, amber-colored sap. As the disease progresses, the plant tissues eventually collapse, leading to wilted foliage and poor fruit development.

Epidemiology of Stagonosporopsis caricae is highly dependent on humidity and temperature. Fungal spores are disseminated via irrigation splash, rainfall, and wind. High relative humidity and warm temperatures create the ideal environment for the spores to germinate and colonize healthy plant tissues.

• Practice strict crop rotation with non-cucurbit crops for at least 3 years.
• Use certified, disease-free, or fungicide-treated seeds.
• Eliminate crop residues to reduce primary inoculum sources in the soil.
• Implement proper canopy management and airflow in greenhouse environments.
• Apply protective and systemic fungicides during high-pressure periods.

The economic impact of gummy stem blight is significant due to both direct loss of yield and the cost of necessary fungicide interventions. If not managed early, the infection can rapidly spread through a field, causing systemic necrosis that destroys the structural integrity of the vines.