Anthracnose
Grape anthracnose, also known as late rot, occurs more commonly in grape growing regions in China. The damage is heavier; in the high temperature and rainy areas in the south, early spring can also cause spoilage of grape flowers.
Symptoms Flowering ear rot: Grapes are susceptible to anthrax in the flowering stage. Flowering ears infected with anthracnose start from the flower florets at the top of the flower, and turn to cobby, florets, and pedicels at the beginning of the flower stem. It is dark brown rot, some rot in the whole ear, and there are several flowers that do not rot during the time. Rotten flowers are easily detached by vibration. When the air is wet, white hyphae and pink viscous substances often grow on the ears of diseased flowers. This is the viscous conidiospores of the bacteria. In the period from March to April in southern China, continuous spring rains occur during flowering and fruit setting. The humidity of the air is very high. Many vineyards often suffer from anthrax rot caused by anthrax, and some of them have a disease rate of 20% to 30%. .
Fruit rot: The fruit is infested, and generally the symptoms are gradually expressed during the maturation period. Lesions are more common in the lower and middle parts of the fruit. They are round or irregular at the beginning, water stains, light brown or purple spots, and later the lesions gradually expand. The diameter can reach 8-15 mm and change to dark brown or black. The peel rots and visibly sag, and the edge shrinks in a rim. Bojian Health Organization has a stiff feeling at the junction. When the air is wet, a small, orange-red viscous spot can be seen on the lesion. This is a conidial spore mass of the pathogen. In the later period, some small grains of grayish-blue color were occasionally seen between or around the pink conidiophore groups, which is the sexual stage of the pathogen. When the onset is severe, the lesions can expand to half or even the entire fruit surface, or several lesions can cause fruit rot. Rotten fruit easily falls off.
Fruiting branches, cobs, petioles, and shoots: After infection, dark brown to black ovals or irregular short strips of pitting lesions are formed. When the air is wet, pink spots are also visible on the lesions. Spore clusters. When fruit stems and cobs are seriously affected, it can affect the growth of the ear and even the shrinkage of the fruit.
?? Leaves: victims of more than in the margin of the edge of a nearly round or oblong dark brown lesions, diameter of about 2 to 3 cm. When the air is wet, pink conidia spores grow on the lesions.
Infection characteristics
The anthracnose pathogen of grapes has the characteristics of latent infection. When the bacteria invade the green part, they become latent, dizzy, and do not expand. After the host is weakened, the bacteria expands again. Therefore, the pathogenic bacteria mainly overwintered on the surface tissue and diseased fruit of the annual dendrite, or overwintered at the leaves, spikes, and nodes. When the spring environmental conditions are suitable, a large number of conidia are produced, and the primary infection is caused by wind and rain, insects spread to the ear.
In Zhengzhou, Henan Province, from about May to June, every time a rain occurs, a batch of conidia is produced, and the spores germinate and invade the skin. The incubation period is 20 days for young fruit and 4 days for fruit in near maturity. The length of the incubation period is related to the content of acid and sugar in the fruit except for the temperature. The high acid content bacteria cannot develop, and no lesion can be formed; the fruit before the hard nuclear stage and the fruit with the reduced acid content in the near maturity period , The bacteria can be active and form lesions; ripe fruits have less acid, more sugar, suitable for the development of pathogens, and the incubation period is short. Therefore, in normal years, the disease started to occur from the middle and late June and gradually increased. After the fruits matured in July and August, the disease entered the peak period.
The diseased part of the annual dendrite is latently contaminated, and the conidia are produced in the second year after winter when the environmental conditions are appropriate. After the initial infection was completed, it fell off together with the diseased skin along with the thickening of the vine, and the new overwintering site was formed on the vine. This is the alternating phenomenon of the new and old overwintering sites that occur on the grapes. . The vines of the two-year-old vines are shed without bacteria, and the old vines are not borne.
Incidence conditions
?? 1, meteorological conditions: germs produce spores need a certain temperature and rainfall. The optimum temperature for the spore production is 28-30°C. Spore heaps appear at the above temperature for 24 hours; spores can also be produced below 15°C, but the required time is longer. As for the amount of spores produced, the extent of wet tissue was used. Temperatures in northern China in the middle and late June can meet the needs of spore production, but the weather is often drought. Therefore, rainfall has become an important factor affecting spore production. If the daily rainfall during this period is 15 to 30 millimeters, spores of germs will appear in the fields, and afterwards, the spores will continue to appear. The high temperature and rainfall of grapes when they are ripe often leads to the epidemic of diseases.
Outside the conidia of the anthracnose pathogen, there is a layer of water-soluble gum, and the conidial mass can only dissipate and spread out when it meets water; the spores need to be heated to a high temperature. Therefore, it is often rainy in summer and the incidence is often severe.
2. Variety: Generally, the varieties with thin peels are more severe, and early-maturing varieties can avoid diseases, and late-maturing varieties often suffer from severe diseases. Eurasian grape species are not suitable for planting in the south because they are very sick.
3. Cultivation and management: Poorly drained orchards, low shelf type, overly dense foliage, poor ventilation, and other environmental conditions are all conducive to hair growth.
Control methods
1. Do a good job in clearing the garden: combine pruning to remove the sub tips, spikes, stamens, tendrils, etc. left on the plants, and completely remove the ear, vine, dead leaves, etc. that have fallen on the ground, and burn them in a concentrated manner to reduce Orchard source. . When the spring grape is sprouting, the spraying of Baume 2-3 degrees lime sulfur plus 200 times of sodium pentachlorophenol, eradicating the source of overwintering bacteria
2, to strengthen the cultivation and management: the growing season to timely picking, vines in a timely manner, so that the orchard good ventilation and light, in order to reduce hair? At the same time must be timely removal of auxiliary shoots, to prevent excessive canopy, is not conducive to the occurrence and spread of the disease. Pay attention to reasonable fertilization, the three elements of nitrogen, phosphorus, and potassium should be properly coordinated, and potassium fertilizer should be added to improve the disease resistance of plants. After the rain, we must do a good job of draining orchards to prevent the accumulation of water in the garden.
3, for some highly susceptible varieties or areas of serious disease, can be used in the young fruit bagging method to prevent Bo?
4. Chemical control: spray protection before flowering, post-flowering, young fruit, fruit expansion and early color conversion. According to climate and disease conditions, the growth season is generally the first time in late June to early July. The medicine is sprayed once every 10-15 days and sprayed 3-5 times. The commonly used agents are 25% of the enemy's demulsification oil 4000-5000 times, or 25% of the 100 grams of EC 500-800 times, 80% of anthrax Fumei WP 500-600 times, 50% of the US WP WP 600 times, 10% Shigao water dispersible granules 1500-2 000 times, 68.75% Yibao water dispersible granules 1 200-1 500 times, 52.5% fast water dispersible granules 2000 times, 53. 8% can kill 2000 dry suspensions 1000 times, 80% Dasong M-45 WP 800 times, 75% Dakkon WP 600 times.
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