Control of spot disease of lobular privet

Lobular Ligustrum lucidum belongs to the genus Ligustrum lucidum of Oleaceae. It is an excellent colored shrub and has been widely planted in recent years. However, with the increase of planting area and the growth of planting years, some of its shortcomings are gradually exposed, especially the old seedlings, there are varying degrees of fallen leaves in the rainy season every year, and occur year after year, seriously affecting the landscape effect.

It is observed that this situation is caused by the spot disease of Ligustrum lucidum. According to the preliminary observation and study, the pathogen of lobular privet spot disease belongs to semi-known subphylum fungi. Round plaques 4 mm to 5 mm in diameter, scattered on leaves.

In wet weather conditions, there are black mildew layers (conidia and conidiophores) on the disease spot. The optimum temperature for the growth of the pathogen was 25 ℃ to 30 ℃, the temperature for conidia germination was 18 ℃ to 29 ℃, and the temperature for infection of the pathogen was 15 ℃ to 27 ℃. The pathogen overwintered with mycelium and conidia on the diseased remains in the soil, and the survival time was about one year. Conidia are mainly transmitted by airflow and Rain Water, invading from stomata and wounds on the plant surface, or directly from the epidermis. The incubation period is 10 to 20 days. At the right temperature and in the presence of water, the spores can germinate in a few hours and the bacteria can be infected repeatedly.

The rainy season began in July and the rainfall gradually decreased in September. During this period, high temperature and high humidity accelerated the occurrence of the disease. The disease began to occur in late July and reached its peak in mid-August, causing a large area of defoliation. The plant began to grow new leaves gradually from the middle to late September, and the color of the leaves darkened in the plots that occurred in successive years, no matter the new leaves or the old leaves. The older the Miao area is, the more serious this phenomenon is. According to the practice for many years, the following prevention and control measures are summarized.

First, the planting site should be conducive to drainage, do not have stagnant water.

Second, the planting density should be reasonable. The higher the plant density is, the more serious the disease is. With the growth of lobular privet, combined with pruning, reasonable pruning, in order to enhance the internal ventilation and light, reduce humidity and temperature.

Third, reduce the source of disease infection. Remove the diseased and disabled bodies from the planting site and remove weeds at any time. This can not only reduce the source of infection, but also increase ventilation and light transmission, which is conducive to creating a healthy growth environment for plants.

Fourth, strengthen fertilizer and water management to increase the resistance of the plant itself. In the aspect of road greening, the soil condition is generally barren, coupled with less fertilization, it is easy to cause plant malnutrition. Fertilizer can be applied once in spring and compound fertilizer combined with rain in the rainy season. It is beneficial to improve the resistance and recovery of Ligustrum lucidum as soon as possible.

Fifth, timely pruning and timely treatment of the wound. Can be re-cut in winter, into the rainy season should reduce pruning, reduce the wound, reduce the chance of germs invading from the wound. Spray fungicides immediately after pruning. Practice has proved that the more frequent pruning in the rainy season, the more serious the disease. In addition, it is necessary to disinfect the pruning tools.

Sixth, drug prevention and treatment. It can be sprayed every 10 days or so from late June until the end of the rainy season in September. The medicament can choose 50% mancozeb wettable powder 500x liquid, 40% Dafudan 400x liquid, 70% methyl topiramate wettable powder 1000 times liquid, 50% carbendazim wettable powder 1000 times liquid. In order to prevent the development of drug resistance of pathogens, agents must be used alternately. The above drugs mixed with 400 milliliters of streptomycin are more effective.

7. The nursery land should be rotated for more than 2 years, and the diseased soil can be treated with formaldehyde solution.