White spot disease on loofah

Luffa white spot disease is a symptom of luffa. When luffa is infected with this disease, its leaf spots will appear circular and irregular in shape. In severe cases, the leaves will turn yellow and the luffa will eventually wither and die. It is contagious to a certain extent, and it is transmitted in the form of mycelium blocks or conidia. We should do a good job of prevention and control in our daily lives. Let us learn about this aspect.

White spot disease of loofah. After infection, moist spots appear on the leaves. They are white at first, then gradually expand and become yellow-white to grayish white or yellow-brown. They are 0.5 to 7 mm in size, with purple to dark brown edges.

Morphological characteristics

Cercospora citrullina Cooke is called melon tail spore and belongs to the subphylum Ascomycota. Stomata absent or small; conidiophores solitary or in bundles, brown, straight or curved, unbranched, without knee-shaped nodes, with 0-4 septa, flat-cut at the apex, obvious spore scars, stalk size 7.5-72.5×4.5-7.75 μm; conidia whip-shaped, colorless or light-colored, with more inconspicuous septa, size 15-112.5×2-4 μm.

The fungus overwinters in the form of hyphae or conidia on diseased remains and seeds. The following year, conidia are produced and spread by air currents and rain, invading through the stomata. After 7 to 10 days of disease onset, new conidia are produced for reinfection. This disease is prone to occur and spread in rainy seasons.

(1) Choose disease-free seeds or use seeds that are more than 2 years old for sowing.

(2) Soak the seeds in 55°C warm water for 15 minutes.

(3) Implement crop rotation with non-melon vegetables for more than 2 years.

(4) In the early stage of the disease, spray 50% carbendazim (carbendazim plus vancomycin) wettable powder 1000 times diluted or 50% benomyl wettable powder 1500 times diluted, 60% anti-mold superfine wettable powder 800 times diluted, 50% polysulfide suspension 600 times diluted, 50 liters of the correct solution per 667m2, once every 10 days or so, and continue to prevent and control 2 to 3 times. Stop using the medicine 5 days before harvest.