Large-leaved boxwood is an excellent landscaping tree species, which can be planted with hedges and background planting materials, or can be planted in the flower territory alone, and they are arranged into a low giant sphere, which is quite beautiful and more suitable for regular symmetrical planting.
Brown spot disease
Brown spot disease is mainly harmful to the leaves of boxwood macrophyllum, and at the beginning of the disease, dark yellow round spots appear on the leaves, and then gradually turn brown. In the summer, high temperature and high humidity are the peak period of the disease, the spots gradually expand into irregular shapes, and the spots become ochre or gray in the later stages of the disease. Heavy ones can cause the leaves to fall off early and weaken the tree. Pathogenic bacteria overwinter on deciduous leaves as mycelium or daughters and form conidia in the spring of the following year. Spreads with wind or rain or watering.
Prevention and control methods
Timely removal of fallen leaves and destruction to reduce the source of infection, early spring spraying of 3-5 baumedo stone sulfur compound to eliminate the source of overwintering bacteria. Strengthen water and fertilizer management, enhance tree potential, improve the disease resistance of plants; strengthen ventilation and light transmission, and prune dense branches in time: spray 50% carbendazim wettable powder 500 times liquid or 75% Bacillus Qing wettable powder 700 times liquid during the onset period, spray once every 7 days, spray 3-4 times continuously.
powdery mildew
Powdery mildew is mainly harmful to the leaves and young shoots of populus macrophylla. At the onset of the disease, there are white round spots on the leaves that are connected to form irregular large spots as the spots continue to expand. White powder may be visible by hand. In severe cases, young leaves are deformed, old leaves are wrinkled, and young shoots are atrophied. Central China has disease from the beginning of March to mid-to-late October, and the pathogenic bacteria overwinter in the gray membranous bacterial layer in late autumn and early winter, and a large number of conidia can be produced in the spring temperature, which can be spread by wind and rain and watering.
In winter, the fallen leaves are removed in time and burned; at the onset of the disease, 70% thiomyprine granules can be sprayed 1000 times liquid, 10% paclobuteric mycin wettable powder 500 times liquid or 25% powder rust rather wettable powder 1000 times liquid, etc., sprayed once every 7-10 days. Spray 3-4 times in a row. It can effectively prevent and control diseases.
Coal pollution disease
Coal pollution disease mainly infects the leaves of large-leaved boxwood, the initial stage of the disease is dotted with soot, and then gradually expanded and connected into pieces, the heavy can cover the entire leaf surface, often appear flakes, cracking, peeling. The disease is caused by the infestation of a variety of coal pollution bacteria, which mainly parasitize excreta and secretions of aphids and mesosomes. It is highly susceptible to illness in shade, high humidity, high temperatures and poor ventilation. Pathogens overwinter on the host plant with mycelium, conidia and ascomycetes, and when excrement or secretions of mesozoans and aphids appear on the host plants in the following spring, conidia and ascospores germinate, infecting the leaves of the plant, and the bacteria can be infected many times, making the disease recur.
Timely control of aphids, mesozoans; planting should not be too dense, timely pruning, strengthen ventilation and light transmission, can be sprayed 0.3 baumedo stone sulfur compound 2 times. Spray every 15 days. In the early stage of the disease, spray 50% carbendazim wettable powder 800 times liquid, 70% methyl tolbuzin wettable powder 1000 times liquid, spray once every 10 days, spray 2-3 times, can effectively alleviate the disease.
Standing blight
At the beginning of the onset of the disease, the upper leaves of individual branches are dried and dehydrated, and then the entire branch and the whole plant are green and dehydrated, and finally the leaves are yellowish white and the whole plant dies. Pathogenic bacteria mostly invade from the root wound 1:3, but can also directly invade the plant. The onset of the disease generally begins in mid-May, and the peak period is from July to August, and some plants do not exceed one week from onset to death.
(1) Strengthen the inspection of the epidemic situation and do not introduce diseased plants.
(2) Strengthen fertilizer and water management, improve plant disease resistance, and keep the cultivation site moist, but can not accumulate water.
(3) If a diseased plant is found, the diseased plant should be uprooted and burned in time. The cultivation site is disinfected with 75% Bacillus Clear Wettable Powder 600 times liquid, with a dosage of 5-6 kg per square, continuously watered 3 times at intervals of 5 days; sulfur powder 0.5 kg can also be fully mixed with the soil for disinfection.
(4) At the beginning of the disease, while irrigating the roots with a fungicide, 50% carbendazim wettable powder 500 times liquid or 65% daisen zinc wettable powder 1000 times liquid can be used to alternately spray the plants, spraying 2-3 times continuously.
Flat-spined moth
The flat-spined moth is mainly a leaf infestation of larvae, and occurs once a year, the old mature larvae overwinter in the shallow soil layer, pupate in May, begin to feather in early June, and the eggs are generally laid on the leaves. The egg stage is 6-8 days, from mid-June to mid-August, and the larvae enter the soil in late August to pupate overwintering. The larvae mostly feed on the leaves. When the amount of occurrence is large, the leaves of the plant can be eaten.
Dig out the overwintering cocoon and kill the wintering spinner insects. Larvae can be sprayed with 500x liquid of Bacillus thuringiensis (bt) emulsion or 25l% cypermethrin emulsion 20oox liquid.
Red Spider
Red spiders are mainly harmful to their leaves, occurring about 10 generations a year. Female adults are fertilized to overwinter on soil masses, fallen leaves and dead branches. Plants can be harmed from mid-to-late March to mid-to-late September, and are more serious during the high temperature and dry season. After the plant is damaged, the leaves are easily shed, which affects the growth.
Before germination in early spring, spray 3-5 baumedo stone sulfur binder to eliminate overwintering adults. The generator can be sprayed with 1.8% avermectin emulsion 6000-8000 times liquid or 30% g mite wettable powder 500 times liquid for control.
Japanese Kameiwasuke
Generations occur once a year, with fertilized female adults overwintering on the branches. Female adult, wax shell gray or slightly flesh red, oval. Male adults, dark brown or brown on the body, the head and thorax dorsal plate is deeper. Nymphs, wax shell ovoid to elliptical, slightly raised dorsal.
(1) Quarantine measures prevention and control: When purchasing seedlings in different places, we must strictly implement plant quarantine procedures to prevent the artificial spread of pests.
(2) Strengthen the maintenance and management of gardens: through conservation management, create environmental conditions that are not suitable for the survival of mesozoans. Implement rotational planting, clear the garden in time, burn the fallen leaves, weeds, diseases and insect branches in a concentrated manner, reduce the base number of overwintering pests and insect mouths, apply fertilizer reasonably, and enhance plant resistance. Reasonable pruning, so that it is ventilated and transparent, changes the living environment of the meseconoids, weakens their fertility, and reduces harm.
(3) Pharmaceutical control: When the density of the insect mouth is not high, it can be wiped out with a soft brush dipped in a small amount of dichlorvos and water (1:50 to 100 times liquid). During the nymph infancy, spray laundry detergent diesel emulsion; 150 to 200 times neem oil emulsion; 1% matrine 1000 to 2000 times liquid; 2000 to 2500 times vigorous killing, spray every 10 days or so, spray 3 times.
(4) Protect natural enemies such as parasitic wasps.