Methods for controlling diseases and pests of weeping cherry
Abstract: This article discusses the related content of weeping cherry, including methods for controlling diseases and pests of weeping cherry. Details are as follows:
Malus brown spot disease
In the south, Malus brown spot disease is one of the most common diseases affecting weeping cherry and is a major cause of premature leaf shedding. The disease can occur throughout the entire growth period of weeping cherry.
In the early stages of the disease, the upper surface of the leaves shows white spots, which gradually expand. After 20 days or so, the white spots turn into brown spots, and the leaves gradually wither and fall off. If left uncontrolled, the leaves may drop by July, and there may be a second blooming. Timely control can keep the leaves until the frost period. Therefore, the disease needs to be controlled throughout the entire growth period of weeping cherry.
Control methods: First, ensure an appropriate planting density, avoid over-planting, and do not plant in shaded, windward areas, as this can lead to severe disease.
Second, based on Zhejiang's climate characteristics, prevent the disease once in mid-to-late April, and then every 20 to 30 days thereafter. Use protective fungicides in the early stages and switch to therapeutic fungicides later. Suggested medications include: before April 15, use 80% mancozeb wettable powder 600 times solution; in mid-to-late May, use 75% chlorothalonil wettable powder 750 times solution; from late May to early June, use 70% methyl thiophanate wettable powder 700 times solution; from late June to early July, use 43% tebuconazole suspension 3000 times solution; from late July to early August, use 25% prochloraz emulsion 1000 times solution; from late August to September, decide whether to continue based on growth conditions, and if necessary, alternate spraying tebuconazole and prochloraz.
Additionally, after the leaves fall in winter to early spring before sprouting, spray once with 45% crystal potassium sulfide 30 times solution or equal parts Bordeaux mixture, which can effectively reduce overwintering pathogens.
Malus rust disease
Malus rust disease generally appears in late April, with early orange spots that gradually expand, causing the affected tissue to thicken, followed by the formation of yellowish-white downy spore structures on the lower leaf surface in May to June. These spore structures are then transferred to Cypress and Juniper trees, returning in April the following year. After the spore structures are released, the affected area turns brown, resembling (T-J) disease or brown spot disease, and the leaves eventually wither and die.
Control methods: First, avoid planting with Cypress, Juniper, and other Cupressaceae trees to prevent the continuous cycle of rust disease.
Second, fungicides commonly used to control Malus brown spot disease are generally effective against Malus rust disease. However, if the disease still occurs widely, special drugs such as 12.5% myclobutanil emulsion 600 times solution, 40% flusilazole water-dispersible agent 7000 times solution, or 20% triadimefon emulsion 500 times solution can be alternated, and using them twice in a row can generally control the disease.
Aphids
Aphids damage the tender shoots and leaves by absorbing sap, causing new shoots to stop growing, leaves to twist and shrink, and also bring sooty mold and virus transmission, making them the main pest in early spring for weeping cherry.
The pest generally appears in early April and gradually decreases by mid-to-late June, with numbers rising again from mid-to-late August until defoliation ends.
Control methods:
1. Physical control: Cut off the tender shoots with pests (considering the impact on seedling growth).
2. Chemical control: Use 70% imidacloprid water-dispersible agent 5000 times solution, 5% lambda-cyhalothrin emulsion 800 times solution, 20% carbosulfan emulsion 1000 times solution, or 70% acetamiprid water-dispersible agent 4000 times solution (not suitable for use in early spring at low temperatures) to control.
Thrips
Thrips damage tender shoots and leaves, especially the tips, with initial damage causing leaves to fail to unfold and thrips hiding inside to absorb sap, making it difficult to detect. Later, the tender shoots and leaves turn yellow-brown and wither, resembling scorching, and are often mistaken for drought or sunburn.
Thrips are tiny insects that are difficult to observe with the naked eye, and their damage is often hidden, requiring careful observation.
This pest has a high tolerance to high temperatures, usually appearing in early May, with severe damage in the high-temperature season of July to August.
Control methods:
1. Physical control:剪去 tender shoots to control damage temporarily (considering the impact on seedling growth).
2. Chemical control: Use 70% acetamiprid water-dispersible agent 4000 times solution, 70% imidacloprid 4000 times water-dispersible agent solution, 50% pymetrozine wettable powder 1500 times solution, or 10% pyridaben aqueous solution 1500 times solution to control.
Net bug
Net bugs generally absorb sap from the leaf veins on the lower leaf surface, causing white spots on the upper leaf surface that eventually connect to form patches, the lower leaf surface turns rusty, thickens, and causes leaf drop, sometimes even defoliation, leading to a second blooming. This pest can appear throughout its entire growth period, but causes more damage after July, becoming the main pest in the summer and autumn seasons for weeping cherry.
Control methods: Net bugs are vulnerable to most insecticides. Considering the principle of integrated pest management, the following pesticides can be used: 70% acetamiprid water-dispersible agent 5000 times solution, 5% lambda-cyhalothrin emulsion 750 times solution, 70% imidacloprid water-dispersible agent 5000 times solution, 25% cypermethrin emulsion 1500 times solution, 1.8% abamectin emulsion 1000 times solution, etc.
Stem sawfly
The stem sawfly is a pest belonging to the Hymenoptera family, with larvae damaging tender shoots, causing the branches to wither and die.
The adult insect usually lays eggs in April, with larvae starting to bore into tender shoots from late April to early May. After being damaged, the tender branches quickly droop and wither, and the pest continues to damage two-year-old branches until August or September.
Control methods:
1. Cut off the infested branches.
2. Use strong systemic or penetrant insecticides for effective control, such as 1.8% abamectin emulsion 500 times solution, 50% fenvalerate soluble powder 700 times solution, 20% carbosulfan emulsion 500 times solution, or 3% high-penetration fenvalerate emulsion 1000 times solution.
Sawfly
The sawfly has many poisonous spines, and contact can cause immediate redness, swelling, and pain, even lymphangitis. Therefore, this pest not only harms the seedlings but also causes significant trouble in daily management.
The young larvae feed on the lower surface of old leaves, leaving transparent net-like veins, while the older larvae consume the entire leaf, showing gregarious feeding behavior, often with several individuals concentrated in one area.
The pest generally appears in June and causes severe damage in August to September, sometimes defoliating the entire plant.
Control methods:
Use 4.5% lambda-cyhalothrin emulsion 700 times solution, 25% cypermethrin emulsion 1500 times solution, 1.8% abamectin emulsion 1000 times solution, 2% methoxychlor emulsion 1500 times solution, 40% phoxim emulsion 300 times solution, etc.
Spider mites
Spider mites primarily damage the lower old leaves, generally parasitizing on the lower leaf surface, with larvae, nymphs, and adults absorbing sap from the lower leaf surface, causing white, chlorotic spots on the upper leaf surface. Severe infestations turn the entire plant gray-white, eventually leading to extensive leaf drop.
The degree of damage caused by this pest is closely related to climate and planting density. Dry, dense planting conditions lead to severe damage, with the southern regions experiencing more damage in the second half of the year than in the first half.
Control methods:
Use 15% pyridaben emulsion 1500 times solution + 5% thiamethoxam emulsion 1000 times solution, 24% spiromesifen 3000 times solution, 50% fenbutatin oxide emulsion 2000 times solution, 20% azocyclotin wettable powder 750 times solution, or 20% binapacryl wettable powder 1000 times solution.
Longicorn
Longicorns are one of the most destructive borers and most devastating pests, with damaged seedlings either weakened or killed.
This pest can live in trees for three years, with larvae boring into the tree for the first two years and emerging as adults in the third year to mate and lay eggs. In the Yangtze River Valley, adult insects emerge and mate from May to September, with June to July being the peak mating period, which is a critical prevention period.
Control methods:
1. In mid-to-late May, based on the emergence of longicorns, spray once with 8% cypermethrin encapsulated microcapsule formulation (green thunder) 200 times solution on the trunk and branching points of the trunk to kill emerging adults, then spray again after 40 to 50 days.
2. For longicorn larvae inside the trunk, inject 5 times carbaryl emulsion or chlorpyrifos emulsion and seal with soil to kill the larvae.
3. For seedlings planted in large areas, release the natural enemy, Trichogramma dendrolimi, and in severe cases, use Trichogramma dendrolimi carrying Beauveria bassiana.
Precautions
1. Weeping cherry requires high light, and should not be planted in shady, wet areas.
2. Due to the mutual cyclic infection between weeping cherry and rust disease of Cupressaceae plants, the two types of plants should not be planted close to each other.
3. During the high-temperature season, weeping cherry is sensitive to carbaryl, omethoate, and potassium sulfide, and these should not be used on the leaves. (Author: Luo Huisheng, Blue Sky Garden)
If the specific content of the weeping cherry pest and disease control methods brought to you can be of help, remember to visit the website often!