Which fungicides are effective for controlling grape black pox?

Before grape flowering, spray 75% chlorothalonil wettable powder at 600—700 times dilution, 80% propineb wettable powder at 800—1000 times dilution, and other fungicides for control. After flowering, in the early stage of disease occurrence, spray 70% thiophanate-methyl wettable powder at 800—1000 times dilution and other fungicides for control. In the middle stage of disease occurrence, spray 40% flusilazole emulsifiable concentrate at 5000—10000 times dilution and other fungicides for control.

I. Brief Introduction to Grape Black Pox

Grape black pox mainly damages the green and tender parts of the grape, such as fruit, fruit stalks, leaves, petioles, new shoots and tendrils. After the leaves are infected, pinhead-sized brown spots appear at first, then develop into yellow-brown round lesions 1-4 mm in diameter, with the center turning gray; finally the diseased tissue dries up and hardens, and falls off to form shot holes. When green fruit is infected, brown round spots appear at first, with the center of the round spots grayish-white and slightly sunken, and the edges reddish-brown or purple, resembling a "bird's eye"; several small lesions merge into large spots, and later the lesions harden or crack. After new shoots, petioles, fruit stalks and tendrils are infected, round brown spots appear at first, then turn grayish-black, with the center sunken into dry, cracked canker spots; in severe cases they finally dry up or die.

II. When does grape black pox occur?

The epidemic of black pox is closely related to rainfall, atmospheric humidity and the tenderness of the plants, and is most closely related to the amount of rain in spring and early summer (April-June). In rainy and highly humid weather, the disease occurs severely; in dry years or areas with little rain, the disease is significantly reduced.

In South China, the disease begins to appear from late March to late April, reaches its peak in mid-to-late June, and is suppressed after July-August; if rainy weather occurs in autumn, the disease can occur severely again. In North China, the disease generally begins in mid-to-late May, with the high-temperature and rainy season from June to August being the peak period, and the disease stops developing after October. In East China, the disease begins in early-to-mid April, with the plum rain season being the peak period; the disease is suppressed in July-August, and if there is much autumn rain in September-October, the disease develops again.

III. What fungicides should be sprayed to control grape black pox?

1. Before grape flowering: spray 80% propineb wettable powder at 800—1000 times dilution, 75% chlorothalonil wettable powder at 600—700 times dilution, 65% zineb wettable powder at 500—600 times dilution, 86.2% copper hydroxide suspension concentrate at 1000—1500 times dilution, 70% mancozeb wettable powder at 600—800 times dilution, and other fungicides.

2. After grape flowering, in the early stage of disease occurrence: spray 70% thiophanate-methyl wettable powder at 800—1000 times dilution, 3% zhongshengmycin wettable powder at 600—800 times dilution, 25% azoxystrobin suspension concentrate at 800—1250 times dilution, 32.5% mancozeb·diniconazole wettable powder at 400—600 times dilution, 65% difenoconazole.azoxystrobin SC (Chuanqi) at 4000 times dilution, 25% tebuconazole aqueous emulsion at 1000—2000 times dilution, and other fungicides.

3. In the middle stage of disease occurrence: spray 40% flusilazole emulsifiable concentrate at 5000—10000 times dilution, 50% imazalil manganese salt wettable powder at 1500—2000 times dilution, 40% thiabendazole wettable powder at 1000—1500 times dilution, 25% prochloraz emulsifiable concentrate at 800—1000 times dilution, 10% difenoconazole water-dispersible granules at 2000 times dilution, 12.5% diniconazole wettable powder at 2000—3000 times dilution, 50% procymidone wettable powder at 800—1000 times dilution, 1.5% polyoxin at 800 times dilution, and other fungicides.