Cotton bolls black fruit disease

Symptoms of the disease are bolls. The bacteria only infects cotton bolls, causing full boll damage. The first light brown shell, full bell soft, after the bell shell was brown, stiff and more than no cracking, the surface of the bell shell dense black spots that pathogenic conidia. At the late onset of the disease, the surface of the bell shell was covered with pulverized coal, and the cotton rot rotted into a black stagnant valve.

The pathogen, Diplodia gossypina Cooke, called a cotton-colored second cell, belongs to the fungus Aspergillus spp. The conidia are black and buried under the epidermis with an opening at the top. Conidiophore stems fine, not branched. Conidia elliptic, colorless, unit cell, dark brown when mature, twin, size 14.4-29.449.6-14.0 (μm). The sexual state Physalospora gossypina Stev. called cottonseed cysts (Brown sphaeroides), belonging to the genus Ascomycoides. Ascendant clustered, black, size 250-300mm. Ascospores 90-120 μm, ascospores solitary, colorless, size 24-427-17 (μm).

Transmission routes and pathogenic conditions The pathogens overwinter on diseased bodies with conidia. The conditions for the leap year are appropriate, and conidia are produced for initial infection and reinfection. Black fungus is one of the primary pathogens causing cotton rotten bells. Blackberries have a wide temperature range and require high humidity. The heavy rainfall is heavy. There are many wounds in cotton bolls, such as insect, mechanical, and burn injuries, which can induce the occurrence of black fruit disease.

Prevention methods (1) Avoid cotton boll damage as much as possible and prevent boll pests in time. (2) Remove the sunning bell in time. (3) Spraying 1:1:200-fold Bordeaux mixture or 70% mancozeb WP 500-fold in the early stage of the disease.