How to prevent and control powdery mildew in cantaloupe cultivation?

Powdery mildew is a major disease of cantaloupe, widely distributed and commonly occurring, occurring both in protected cultivation and in open fields, severely affecting cantaloupe yield and quality.

Symptoms can occur throughout the entire growth period, and it can infect leaves, petioles and stems. Initially, small white powdery spots form on the leaf surface, and multiple lesions merge into large irregular patches, after which the leaf surface becomes covered with white powder, namely the pathogen's conidiophores and conidia. As the disease develops, the diseased leaves gradually age and die, and sometimes small black dots, namely the pathogen's perithecia, are produced on the necrotic lesions. When petioles and stems are infected, white powdery mildew spots also appear on the surface, and in severe cases the lesions are densely distributed, the tissues age prematurely, and death occurs.

The pathogen Sphaerotheca fuliginea (Schl.) Poll. is called monoclinous-shell powdery mildew fungus, belonging to the Ascomycota fungi. The pathogen's conidiophores are cylindrical, colorless, unbranched, with conidia borne in chains at the apex. Conidia are single-celled, colorless, oval, measuring 18.4-36.8μm×14.5-20.1μm. The sexual stage cleistothecia are rarely produced.

Disease characteristics: The pathogen overwinters with diseased residues in protected cultivation areas, and conidia can also overwinter by damaging other hosts, spreading via airflow and rainwater. The pathogen prefers warm and humid conditions and tolerates dryness; alternating high temperature and dryness with humidity favors disease occurrence and development. The pathogen's growth temperature is 10-30℃, the optimum temperature is 20-25℃, and conidia can germinate at a relative humidity of 25%-85%, with high humidity conditions being suitable for disease development. In the mid-to-late growth stage, plants grow weakly and the disease is severe.

Prevention and control methods

(1) Select and plant disease-resistant varieties according to local conditions.

(2) Strengthen cultivation management.

Adopt high-ridge planting, rational close planting, and pay attention to ventilation and air permeability; fertilize scientifically, apply sufficient base fertilizer at planting, increase the application of phosphorus and potassium fertilizers, avoid fertilizer deficiency in the later stage, and cultivate strong seedlings; irrigate at the right time, pay attention to combining drainage and irrigation, and prevent excessive field humidity; prune and remove side shoots in time, and promptly pull out diseased plants when found.

(3) Chemical control.

In protected cultivation, it is recommended to use a sulfur fumigator for regular fumigation prevention.

In the early stage of disease, choose 2% Nongkang 120 aqueous solution, or 2% Wuyi mycin aqueous solution at 200-300 times dilution, or 43% Junlike suspension concentrate at 8000 times dilution, or 10% Shigao water-dispersible granules at 8000 times dilution, or 40% Fuxing emulsifiable concentrate at 8000 times dilution, or 25% Bailitong wettable powder at 2500 times dilution, or 30% Tefuling wettable powder at 4000 times dilution, or 25% triadimefon wettable powder at 1000-1500 times dilution for spraying. In protected cultivation, in the early stage of disease, choose 5% chlorothalonil dust or 5% Jiaruinong dust, or dust formulations of the above spray agents at 15kg/hm2 for dusting, and the control effect is ideal.

Commonly used agents: Nongkang 120, Wuyi mycin, Junlike, Shigao, Fuxing, Bailitong, Tefuling, triadimefon, chlorothalonil, Jiaruinong.