Grape Anthracnose Control Methods and Fungicide Recommendations

Grape anthracnose is one of the diseases most likely to occur during the grape ripening period. When it strikes, it first produces pinhead-sized spots on the fruit surface, which then gradually expand and eventually cause large areas of rot. In some places it is also called late rot. So what do grape anthracnose pictures look like? How should grape anthracnose be controlled? What is the best fungicide to spray for grape anthracnose?

How is grape anthracnose treated? What fungicide is best to spray?

1. Existing Problems

1 Fungicide use habits. According to on-site surveys, most fruit growers still use conventional fungicides such as mancozeb, thiram, carbendazim and thiophanate-methyl to control anthracnose. Triazole fungicides and some new products are rarely used. Moreover, they are used many times a year, which leads to resistance. The control effect on anthracnose is very poor.

2 Timing of fungicide application. Fruit growers generally do not use good fungicides until they see the disease. They also neglect prevention before flowering, after flowering, and from after flowering to the young fruit stage. This gives the pathogen opportunities to infect and remain latent. It causes a major outbreak of the disease.

2. Grape Anthracnose Control Methods

1 The pathogen of grape anthracnose and its occurrence pattern. The pathogen is Colletotrichum gloeosporioides. The pathogen mainly overwinters as mycelium in the fruiting canes, the surface tissues of 1-year-old canes, diseased fruit and other places. In the second year, during the young fruit stage, it produces large numbers of conidia. They are spread by wind and rain to the young clusters. They invade through lenticels and wounds. This forms the primary infection, which has latent characteristics. The disease develops at the coloring stage, and it can also cause multiple secondary infections. This causes a major outbreak of the disease. At the early stage of the disease, water-soaked or snowflake-like lesions appear on the fruit. They then gradually expand to form dark brown sunken spots. Dense black small granules are arranged in concentric rings. When air humidity is high, red gelatinous material appears. In severe cases, the diseased fruit loses water and shrivels, and drops off very easily. At the same time, it can also damage fruit stalks, rachises, young shoots and petioles.

Anthracnose occurs relatively late in the field. It generally begins to occur in early July. In the fruit ripening period of August-September, the disease enters its peak period. There is more rainfall in summer and autumn, and high temperatures during the near-ripening period of the fruit favor the disease.

2 Control of grape anthracnose.

① In combination with winter pruning, thoroughly clean the orchard. Remove all pruned canes, cluster stalks, berries, tendrils, fallen leaves, and ties on the wires from the orchard, and burn or deeply bury them in a centralized manner. Reduce the overwintering sources of inoculum.

② Pinch the tips in time, carry out reasonable summer pruning, and keep an appropriate load. Promptly remove the pruned young shoots and tendrils to improve ventilation and light penetration in the orchard, pay attention to intertillage and drainage, and reduce the humidity in the orchard as much as possible.

③ Apply fertilizer scientifically and reasonably. Increase the application of organic fertilizer and potassium fertilizer. Pay attention to the ratio of nitrogen, phosphorus and potassium, and avoid excessive nitrogen fertilizer. Also replenish medium and trace elements in time. This strengthens the tree vigor and improves resistance.

④ Chemical control.

In spring, before the young buds sprout, spray 3-5 degrees Baume lime sulfur mixture.

Before and after grape bud break, spray 1:0.7:200 Bordeaux mixture, or 80% mancozeb wettable powder at 300-500 times dilution.

At grape fruit drop stage, in the early stage of disease occurrence, spray the following fungicides: 50% carbendazim wettable powder at 600-800 times dilution, or 80% mancozeb wettable powder at 600-800 times dilution, or 70% propineb wettable powder at 600-800 times dilution, etc.

The young fruit stage of grapes is the key period for control. The following fungicides can be used: 2% pyrimidine nucleoside antibiotic aqueous solution at 200 times dilution, or 1% zhongshengmycin aqueous solution at 250-500 times dilution, or 35% propiconazole·carbendazim suspension concentrate at 1400-2000 times dilution, or 25% prochloraz emulsifiable concentrate at 800-1500 times dilution, or 60% thiabendazole wettable powder at 1500-2000 times dilution, or 10% difenoconazole water-dispersible granules at 2000-3000 times dilution, etc., for spraying, with 3-5 consecutive sprays at 10-15 day intervals.