What are the control measures for grape black pox?

Grape black pox, also known as scab, and called “bird's eye disease” in some areas, can harm most of the green tender tissues of grapes, mainly affecting the fruit, fruit stalks, leaves, leaf stalks, new shoots and tendrils. Black pox is one of the common diseases in the grape growing process; its appearance greatly affects the commercial value of grapes and brings certain economic losses to grape growers. So how should we prevent and control black pox? Qinnong Network today introduces the control measures for black pox.

I. Symptoms of black pox

Grape black pox occurs most intensively in spring and early summer, and is also the earliest disease to appear during the grape growing period. When young leaves are infected, brown spots the size of pinheads appear on the leaf surface; after the spots expand, there is a yellow-brown halo around them, and they gradually become irregular in shape, with the center of the spot turning light brown or gray-white and the edges dark brown; in the later stage the tissue at the center of the spot dies and falls off, forming holes. The spots are fairly uniform in size, with a diameter of 2—4mm. When new shoots, leaf stalks and tendrils are infected, round or irregular small brown spots appear, later turning gray-black, with the edges of the spots dark brown or purple-brown and the center sunken and cracked. In severe cases, several spots often merge into one, causing the diseased shoots and tendrils to die because the spots girdle them. When young fruit is infected, small round brown spots first appear, then the center of the spot turns gray-white with purple-brown edges, slightly sunken, resembling a “bird's eye”; in the later stage the spots harden or crack, and the diseased fruit is small and deformed, with no edible value. When growing berries are infected, the berries can still enlarge, the spots have no obvious sunken areas, and the taste is sour. When the air is humid, a gray-white sticky substance (conidial mass) forms on the spots. When the rachis is infected, it often causes poor development of part of the cluster or even the whole cluster, or even death.

II. Control methods for black pox

The control of black pox also follows the concept of giving priority to prevention and supplementing with treatment, first eliminating the possibility of disease outbreaks from the source. Qinnong Network here introduces four control methods for everyone; among them only the last uses pesticide control, while the first three focus mainly on routine care. Let's take a specific look below:

1. Eliminate overwintering sources of disease

Prune carefully, cutting away diseased branches, diseased fruit clusters and tendrils completely; bury fallen leaves deeply and remove diseased debris promptly, burying it deeply or burning it; when the buds swell, carefully spray 3-5 degree Beaume lime sulfur mixture or 45% crystal lime sulfur 30-40 times solution, or 100 times sodium pentachlorophenate to eliminate overwintering pathogens.

2. Choose drip-free anti-fog film to cover the facility

Cover the entire ground area inside the facility with plastic film, and pay attention to ventilation and dehumidification to reduce the air humidity inside the facility, keeping relative air humidity below 80%, inhibiting spore germination and reducing infection.

3. Deep plowing and soil improvement

Deepen the active soil layer to promote root development; increase the application of organic fertilizer, phosphate fertilizer, potassium fertilizer and trace element fertilizer; appropriately reduce the amount of quick-acting nitrogen fertilizer to improve the plant's own disease resistance. Use reasonable density, scientific pruning, appropriate shoot retention and reasonable load, maintain vigorous growth, improve field light conditions, and reduce air humidity in the microclimate. Bag the fruit clusters to eliminate infection of the clusters by pathogens.

4. Chemical control

Protectants: 78% Kobo 600-800 times, 80% Bibei 400 times; 80% Dacotech M-45 or 80% Pencozeb 600-800 times, 1:0.5:200 Bordeaux mixture;

Therapeutic agents: 5% mebanizing (imibenconazole, amide azole) 800-1000 times, 10% Score (difenoconazole) 1500-2000 times, 12.5% Sumiseven (diniconazole) 3000-4000 times, 40% flusilazole (Fuxing) 8000-10000 times; 50% carbendazim 600-800 times, 70% thiophanate-methyl 800-1000 times.

The above are the control measures for grape black pox brought to you by Qinnong Network. As a common disease that harms grapes, the control of black pox is of great significance to grape growing, and we hope this article can provide some reference value for growers.