1. Kiwi leaf spot
Damage symptoms
When the leaves are infected, they initially form round, nearly round or irregular reddish-brown spots, which then continue to expand and extend along the leaf margins, so that multiple spots are united, but most of the spots are small due to the restriction of leaf veins. The spots are slightly lighter in color in the later stage, some are gray, and there are small black dots on the surface.
Prevention and control methods
① Select disease-resistant varieties in serious disease areas. Increase the application of organic fertilizers, prune reasonably, enhance tree vigor, and improve disease resistance.
② At the early stage of the disease, spray 1000 times of 70% methyl thiophanate wettable powder, 1000 times of 80% mancozeb wettable powder, 2000 times of 25% azoxystrobin suspension, or 1500~2000 times of 10% difenoconazole water-dispersible granules, spray once every 7~10 days, and spray 3 times continuously.
2. Gray mold of kiwifruit
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Symptoms
Leaves are infected, and the edges or tips of leaves become brown and slightly striated after infection. When it is humid, a large amount of gray mold grows on them.
Flowers are infected, and they are initially water-soaked, and then gradually turn brown and rot, with a large amount of gray mold on the surface.
Fruits are infected, and the lesions are initially water-soaked brown, and then a large amount of gray mold appears, rots and deteriorates, and loses its edible value. Sometimes black irregular sclerotia are formed in the rotten part.
Prevention and control methods
①Strengthen fertilizer and water management to enhance the disease resistance of trees; ventilate and light to reduce the high reproduction of pathogens, remove diseased and insect-infested branches, overcrowded branches, and parallel branches to enhance tree vigor; clean the garden in winter, burn the diseased and residual bodies in a centralized manner, and reduce the source of overwintering diseases.
② At the end of the flowering period, spray 50% carbendazim WP 800 times, or 75% thiophanate-methyl WP 600 times, or 50% isoprodinil WP 800 times, or 70% mancozeb WP 600-800 times, once every 7-10 days.
3. Kiwi soft rot
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Damage symptoms
The fruit is infected, the initial lesions are light brown, surrounded by yellow-green, and the junction of the diseased and healthy is a dark green halo. The flesh is light yellow, with a spongy cavity inside; in the middle and late stages, the lesions gradually become sunken, nearly round or oval, brown, and often have a conical rot point in the center. The epidermis does not break, but it is easy to separate from the flesh.
Prevention and control methods
① Strengthen orchard management, apply basal fertilizer, apply topdressing in time, and enhance tree vigor; reduce the shade of the garden, improve ventilation and light conditions; thoroughly clean the garden in winter, clean up fallen leaves and fruits, cut off diseased branches, and eliminate pathogen carriers; bag young fruits; avoid fruit bruises during harvesting and transportation; store at low temperatures.
② Spray 3-5 degrees Baume lime sulfur mixture on the whole garden before budding in spring. Spray 1000 times of 80% methyl thiophanate wettable powder from 2 weeks after flowering to the fruit expansion period.
4. Kiwifruit sclerotinia disease
Damage symptoms
The male flowers are initially water-soaked, then soften, and then wither and die in clusters, shrinking into brown masses; the female flowers are damaged and the buds turn brown, wither and cannot bloom. Under rainy conditions, white mold grows on the diseased part.
When the fruit is damaged, it initially shows water-soaked chlorotic patches, the diseased part is sunken, and gradually turns to soft rot. The diseased fruit is not resistant to storage and transportation and is easy to rot. In the field, fruits with serious disease generally fall off one after another; a few fruits shrink due to rotten flesh, cracked peel, and overflow of rotten juice; in the later stage, irregular black sclerotium particles appear on the surface of the diseased peel.
Prevention and control methods
① Prune and clean the garden in winter, and bury the topsoil 10~15cm after fertilization, so that the sclerotium is buried deep in the soil and cannot germinate and infect.
② In the early stage of the disease, spray 1000 times of 50% ethephon wettable powder, or 1000 times of 40% sclerotinia net wettable powder, or 1000 times of 50% isoprodinil wettable powder, or 1000 times of 50% procymidone wettable powder, and carry out prevention and control twice in a row, with good prevention effect.
5. Kiwi root knot nematode
Damage symptoms
Small swellings or small tumors are produced on the affected tender roots of the plant, and they become large tumors after several infections. The tumors are white at the beginning, then turn light brown, then dark brown, and finally turn black brown. Plants affected by root-knot nematodes have poor root development, a large number of tender roots die, fine roots are in clusters, roots have few branches, and they grow short, which has a greater impact on young trees.
Prevention and control methods
① Strict quarantine: When developing new kiwifruit orchards, the planted seedlings must be strictly inspected, and seedlings with nematodes must never be used. Use nematode-resistant rootstocks. Nurseries should not be planted continuously, and nematicides should be applied to diseased areas before sowing. Strengthen cultivation management to enhance tree vigor and improve disease resistance. Severely diseased seedlings should be removed in time and burned in a centralized manner.
② Treatment of diseased seedlings: Cut off the nodules on the roots of seedlings before planting, and soak the roots in 48℃ warm water for 15 minutes to kill the nematodes in the nodules.
③ For gardens with severe disease, 3~5 kg of 10% chlorpyrifos per mu should be used for furrow application before planting, and then turned into the soil. For plants with mild disease, 10% chlorpyrifos can be applied in the 5-10 cm soil layer under the crown. Watering is required after application, which also has a control effect.
6. Kiwi rough skin disease
Harm symptoms
Symptoms begin to appear from the young fruit stage, only the skin is damaged, which is brown to dark brown. The affected epidermal tissue is corky and scabby. The skin is very rough, making the fruit lose its commercial value.
Prevention and control methods
① Appropriately thin flowers and fruits and bag young fruits. Start bagging young fruits one week after flowering to avoid infection. Remove pruned branches and dead branches and leaves, and burn them in a centralized manner to reduce the parasitic sites of pathogens.
② Spray 50% carbendazim wettable powder 800 times liquid, or 1:0.5:200 times Bordeaux mixture, or 80% thiophanate wettable powder 1000 times liquid on the crown from 2 weeks after flowering to the fruit expansion period. Spray 2-3 times, with an interval of about 20 days between spraying.
7. Kiwifruit blossom rot
Damage symptoms
For severely affected plants, the buds cannot swell, the calyx turns brown, the buds fall off, and the filaments turn brown and rot.
For moderately affected plants, the flowers can bloom, the petals are orange-yellow, the stamens turn black-brown and rot, the pistils turn brown, the stigma turns black, and the ovary is also infected on rainy days. Although some female flowers can be pollinated and fertilized, the base of the pistil does not swell.
The disease also causes abnormal kiwifruit fruits, with few or no seeds. Most affected fruits fall off within a week after flowering; for slightly affected plants, the ovary of the fruit swells, forming deformed fruits or the heart column of the fruit turns brown, and the top of the fruit turns brown and rots.
Prevention and control methods
① Strengthen the management of orchard fertilizer cultivation to improve the disease resistance of the tree. In autumn and winter, deep plowing and digging should be done to increase the application of a large amount of decomposed organic fertilizer to keep the soil loose; in spring, quick-acting phosphorus fertilizer should be used as the main fertilizer, combined with quick-acting phosphorus and potassium fertilizer and trace element fertilizer; in summer, quick-acting phosphorus and potassium fertilizer should be used as the main fertilizer, combined with appropriate amounts of quick-acting nitrogen fertilizer and trace element fertilizer.
② Timely inter-cultivation and weeding should be carried out to improve the garden environment. In particular, in Pingba District, drainage ditches should be kept unobstructed from May to September to reduce the humidity of the garden and timely pick out diseased flowers and fruits from the kiwifruit garden for treatment to reduce the number of disease sources.
③ In winter, 5 degrees Baume lime sulfur mixture should be used to spray the entire garden thoroughly; during the budding period of kiwifruit, 3-5 degrees Baume lime sulfur mixture should be used to spray the entire garden; during the leaf expansion period, 65% mancozeb or mancozeb 500 times solution or 50% thiophanate 800 times solution or 0.3 degrees Baume lime sulfur mixture should be used to spray the entire tree, and spray once every 10 to 15 days, especially in the early flowering period of kiwifruit, it is necessary to prevent it again.
