Garden Plant Pests and Diseases Prone to Occur in September and Their Control Methods
By September, autumn is the peak period for the occurrence and damage of garden plant pests and diseases. During this period, close attention should be paid, with active prevention and timely treatment, so as to minimize the damage caused by various pests and diseases to garden plants.
Main Diseases in September
1. Lawn leaf blight
Symptoms: Withered patches of varying sizes appear on the lawn; the grass plants fade from green to withered yellow; the roots, root crowns and root collars of the grass plants turn dark brown; the outer cortex of the vascular bundles rots, and the whole plant dies.
Control methods for lawn leaf blight:
① 64% duishafan (ferrous ammonium sulfate) 600-700 times dilution; ② 70% mancozeb 500-600 times dilution; ③ 50% meimeiling 500-600 times dilution; ④ 90% fosetyl-aluminium 500-600 times dilution.
2. Lawn brown patch (Rhizoctonia solani blight)
Symptoms: It infects the leaves, sheaths and stems of lawn plants, causing leaf rot, sheath rot and stem base rot. Individual leaves develop brown spindle-shaped or elongated lesions 5-50 mm long, initially bluish-gray, later dark brown, and in severe cases the lesions encircle the stem. The entire leaf becomes water-soaked and rots, and the tillers of diseased plants mostly die. Near-circular dead grass patches 1-2 m across appear on the lawn; in warm, humid conditions a "smoke ring" appears, which later becomes a "frog-eye" pattern with a green center and withered yellow margins.
Control: ① 70% mancozeb 500-600 times dilution; ② 70% thiophanate-methyl 600-700 times dilution; ③ 50% meimeiling 500-600 times dilution; ④ 72.2% propamocarb aqueous solution 800 times dilution + 50% thiram 800 times dilution for spraying and drenching.
3. Rose black spot
Control method: Spray 80% zineb 600 times dilution or 50% carbendazim 500-600 times dilution.
4. Cherry brown spot
Control method: Spray 58% ridomil MZ 500 times dilution or 50% kasugamycin-copper 1000 times dilution.
5. Euonymus japonicus wilt
Control method: Drench with 50% zineb wettable powder 500 times dilution.
Various Pests in September
1. Phalera flavescens: commonly known as the boat-shaped caterpillar
Hosts: Many plants such as flowering almond (Prunus triloba), crabapple, cherry blossom, cherry, peach, elm, and papaya.
Pattern: One generation occurs per year; adults emerge in July, and larvae hatch and cause damage from August to October. In late autumn they enter the soil to pupate and overwinter. The larvae have 5 instars and exhibit clustered damage, silk-thread dropping and thanatosis (playing dead); they feed day and night with a very large appetite, and in a single night can strip the leaves from an entire branch or even an entire tree.
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Garden Plant Pests and Diseases Prone to Occur in September and Their Control Methods
News from China Garden Network on September 6: By September, autumn is the peak period for the occurrence and damage of garden plant pests and diseases. During this period, close attention should be paid, with active prevention and timely treatment, so as to minimize the damage caused by various pests and diseases to garden plants.
Main Diseases in September
1. Lawn leaf blight
Symptoms: Withered patches of varying sizes appear on the lawn; the grass plants fade from green to withered yellow; the roots, root crowns and root collars of the grass plants turn dark brown; the outer cortex of the vascular bundles rots, and the whole plant dies.
Control methods for lawn leaf blight:
① 64% duishafan (ferrous ammonium sulfate) 600-700 times dilution; ② 70% mancozeb 500-600 times dilution; ③ 50% meimeiling 500-600 times dilution; ④ 90% fosetyl-aluminium 500-600 times dilution.
2. Lawn brown patch (Rhizoctonia solani blight)
Symptoms: It infects the leaves, sheaths and stems of lawn plants, causing leaf rot, sheath rot and stem base rot. Individual leaves develop brown spindle-shaped or elongated lesions 5-50 mm long, initially bluish-gray, later dark brown, and in severe cases the lesions encircle the stem. The entire leaf becomes water-soaked and rots, and the tillers of diseased plants mostly die. Near-circular dead grass patches 1-2 m across appear on the lawn; in warm, humid conditions a "smoke ring" appears, which later becomes a "frog-eye" pattern with a green center and withered yellow margins.
Control: ① 70% mancozeb 500-600 times dilution; ② 70% thiophanate-methyl 600-700 times dilution; ③ 50% meimeiling 500-600 times dilution; ④ 72.2% propamocarb aqueous solution 800 times dilution + 50% thiram 800 times dilution for spraying and drenching.
3. Rose black spot
Control method: Spray 80% zineb 600 times dilution or 50% carbendazim 500-600 times dilution.
4. Cherry brown spot
Control method: Spray 58% ridomil MZ 500 times dilution or 50% kasugamycin-copper 1000 times dilution.
5. Euonymus japonicus wilt
Control method: Drench with 50% zineb wettable powder 500 times dilution.
Various Pests in September
1. Phalera flavescens: commonly known as the boat-shaped caterpillar
Hosts: Many plants such as flowering almond (Prunus triloba), crabapple, cherry blossom, cherry, peach, elm, and papaya.
Pattern: One generation occurs per year; adults emerge in July, and larvae hatch and cause damage from August to October. In late autumn they enter the soil to pupate and overwinter. The larvae have 5 instars and exhibit clustered damage, silk-thread dropping and thanatosis (playing dead); they feed day and night with a very large appetite, and in a single night can strip the leaves from an entire branch or even an entire tree.
Control: ① Spray 10% duolaibao suspension concentrate 1500-2000 times dilution; ② Spray 2.5% deltamethrin emulsion 1000-1500 times dilution; ③ Spray 20% jusha emulsifiable concentrate 1500-2000 times dilution.
2. Slug moths (Limacodidae)
Hosts: In addition to generally damaging plants of the Rosaceae family, they also damage more than 100 species of plants including plane tree, walnut, jujube, persimmon, pomegranate, ash, and mulberry.
Pattern: This insect has one generation per year; adults emerge in July, and larvae hatch and cause damage from August to October. They feed exclusively on leaves, first producing a net-like pattern, then notches and holes, until the leaves are completely eaten.
Control: ① Spray 20% diflubenzuron 5000-6000 times dilution, or diflubenzuron No. 3 suspension concentrate 2000-2500 times dilution; ② Spray Bt emulsion 500 times dilution; ③ Spray 2.5% deltamethrin 1000-1500 times dilution, or 20% jusha emulsifiable concentrate 1500-2000 times dilution, or 10% duolaibao suspension concentrate 1000-2000 times dilution, or sulibao suspension concentrate 800-1000 times dilution. ④ Protect natural enemies such as ichneumon wasps, braconid wasps, assassin bugs, and mantises.
3. Aromatic goat moth (Cossus cossus)
Control: Since the larvae crawl out of tree holes and enter the soil in late September to spin cocoons and overwinter, a ring of "chuchongjing" powder can be scattered on the soil surface around the base of the trunk to kill the larvae entering the soil (but attention must be paid to environmental safety; do not let poultry, pigeons, or pets come into contact and be poisoned).
4. Japanese wax scale (Ceroplastes japonicus)
Hosts: Plane tree, Euonymus japonicus, etc.
Control: Spray 40% supusha 1000-1500 times dilution.
5. Others
(1) Various longhorn beetle larvae
September is another peak period for most longhorn beetle larvae boring and causing damage. There are generally two types of damage:
① Shallow-layer damage - larvae hatched in the current year bore and damage the phloem; there are no obvious frass holes on the tree surface, and no frass on the ground.
② Deep-layer damage - larvae hatched last year or the year before bore and damage the xylem; there are obvious frass holes on the trunk, with frass accumulated outside the holes or scattered on the ground along with wood shavings.
Control: For larvae causing shallow-layer damage, brush the trunk with a concentrated 40% monocrotophos solution at 100-500 times dilution, which has strong systemic action. For larvae causing deep-layer damage, after clearing the frass from the frass holes, insert and plug "zinc phosphide" poison sticks, then seal the openings with mud to form a sealed "gas chamber," so that the "phosphine" gas released after the poison sticks become damp permeates everywhere inside the trunk and fumigates the larvae, giving good results.
(2) Leaf-eating pests: the 4th-generation larvae of the pagoda tree looper (Semiothisa cinerearia), poplar lappet moth larvae, hawk moth larvae, etc.
Control: Spray diflubenzuron No. 3 suspension concentrate 2000-2500 times dilution, or Bt emulsion 500 times dilution, or 2.5% deltamethrin 1500-2000 times dilution.
(3) Piercing-sucking pests: red spider mites, scale insects, thrips, whiteflies, aphids, etc.
Control: Spray ① 15% saomanjing 1000-1500 times dilution (red spider mites); ② 40% supusha 1500-2000 times dilution (scale insects); ③ 20% puchongling 1000-1500 times dilution (whiteflies, psyllids); ④ 10% imidacloprid 1000-2000 times dilution (whiteflies, aphids); ⑤ 1.2% nicotine-anabasine emulsifiable concentrate 800-1000 times dilution (thrips, aphids).
For the control of piercing-sucking pests, whether the affected plants are trees, flowering shrubs, herbaceous flowers, potted flowers, or herbaceous perennials, applying "tiemieke" (aldicarb) technical material buried in the soil at 3-5 g per sq m, or at 2-3 g per cm of trunk diameter at breast height, gives good results with a long residual effect.
Control of Common Pests and Diseases of the Garden Plant Salix integra (shrub willow)
The control of pests and diseases of Salix integra is a key link in its production and management, directly affecting its growth, quality and yield. Therefore, by understanding the growth characteristics of Salix integra, grasping the timing and patterns of pest and disease occurrence, and adopting corresponding control measures, the occurrence of various pests and diseases can be reduced. Based on practical experience, the author briefly introduces the types and control of common diseases and pests of Salix integra.
1. Types and Control of Salix integra Diseases
1) Salix integra jaundice disease
Salix integra jaundice disease is the main disease of Salix integra, especially in autumn, when its impact is greatest. In severely affected plots, infection can reach more than 80%, and Salix integra yield is reduced by 50%. Salix integra jaundice disease is caused by viruses and mycoplasma-like organisms. It often occurs in autumn when Salix integra has grown to about 20 cm, with the peak period around the Autumn Equinox. When the disease occurs, the leaves noticeably turn yellow and white, the young leaves curl backward, growth stops, and dwarfing is especially severe, potentially causing the entire plant to die.
For Salix integra jaundice disease, quarantine should be strengthened; infected plants are prohibited from being transported out or used as planting stock, to prevent the spread of the virus. In susceptible areas, high-quality varieties such as Xinyiliu, benliu, and huangpiliu should be selected. Fertilizer and water management should be strengthened to enhance clump vigor,
improving disease resistance. Harvesting should be done during the first fu period (mid-July to mid-August) to enhance the autumn growth vigor of Salix integra.
In plots where jaundice disease occurs, a commonly used control measure is to spread plant ash in the morning when there is dew, which can have a controlling effect. For chemical control, carbendazim or Bordeaux mixture at 1000 times dilution with water can be sprayed, and it can be used together with other insecticide chemicals at the time of spraying.
2) Salix integra nematode disease
Salix integra nematode disease has a great impact on the growth of Salix integra. Newly planted plots and old plots are susceptible to this disease. When the disease occurs, whole clumps or patches die. The rooted parts appear swollen and thick, the roots bear white hairs, the lateral roots gradually rot, the fine roots turn black, and the plant dries up and dies
from bottom to top.
For the control of Salix integra nematode disease, crop rotation should be practiced. In plots where more than 30% have died, the plants should be cut down immediately and the crop changed; replanting the following year is prohibited. The rotation interval should be 2-3 years; after 3-5 consecutive plantings, it is best to plant crops. The longer the rotation period, the better the effect.
For chemical control, soil disinfection can be used. Before planting new Salix integra, when preparing the land, apply 80% dibromochloropropane at 3 kg per mu (1 mu = 1/15 ha) mixed with 100-200 kg of water, applied underground, which has a certain control effect.
2. Types and Control of Salix integra Pests
1) Scarab beetles
There are many species of scarab beetles. Those that seriously harm Salix integra include the brown scarab, the black velvet scarab, and the copper-green scarab. The larvae of scarab beetles are called white grubs, commonly known as "soil silkworms," and are underground pests that harm the roots of seedlings.
Scarab beetles produce one generation per year, with larvae overwintering in the soil. Each year from April to May, adults begin to be active, most numerous on stuffy summer evenings, nibbling tender leaves, and at dawn they fly off and hide in the soil at a depth of 1 cm. Adults have habits of clustering and thanatosis (playing dead). In view of the living habits of scarab beetles, when preparing the land, 812 should be applied underground together with fertilizer to kill the larvae. Adults can be caught by hand, or lured and killed at night by building a fire or lighting a lamp at the edge of the field. For chemical control, 90% trichlorfon 1000 times dilution can be sprayed, or 812 powder at 50 times dilution can be broadcast to kill adults.
2) Willow looper
The willow looper, commonly known as the inchworm or bowed worm, occurs in many places. The larvae feed on willow buds and leaves, with the third-generation overwintering larvae causing the most serious damage; it is one of the pests harming Salix integra in spring and autumn.
In Jiangsu, Shandong, Anhui and most of the Huang-Huai region, the willow looper has three generations per year, overwintering as the last-generation larvae. In early spring of the following year, before the winter buds turn green, it begins to be active, gnawing on shoot buds. After 2-3 molts, it spins silk on the main stem or in folded leaves,
forms a cocoon and pupates. Adults are active at night and are phototactic. They lay eggs on the underside of tender leaves at the shoot tips, clustered together in groups of several hundred.
For the control of the willow looper, it can be captured at any time during routine pruning of side branches. In winter, fallen leaves in the field should be promptly swept up and burned in a centralized manner. It can also be controlled by spraying 50% phoxim emulsion at 500-1000 times dilution before the willow buds grow (early to mid-March). In mid-to-late August, when the third generation of larvae occurs, it can be killed by spraying 1605 solution. Natural enemies (black-waisted yellow wasps) can also be used for control, achieving pest control by pests.
3) Willow caterpillar
The willow caterpillar is commonly known as the golden-haired caterpillar or venomous caterpillar. It occurs in many willow fields in various places. The larvae have venomous hairs on their bodies that can cause redness, swelling and pain in humans. The larvae are the main damaging stage, and it is one of the major pests of Salix integra.
In southern Shandong and south-central Shandong, the willow caterpillar has 2-3 generations per year. Third- and fourth-instar larvae hide in fallen leaves at the root zone to overwinter. In April of the following year, they break out of their cocoons and become active, mostly congregating on the underside of leaves to feed on the leaf mesophyll, leaving block-shaped transparent patches on the leaf surface. The larval occurrence periods of each generation are late May, early to mid-August, and late September. Adults are phototactic and lay eggs on the underside of leaves. After 5-7 molts, they form thin cocoons in the clumps or within willow leaves and pupate.
Winter management of Salix integra plots should be strengthened, and fallen leaves should be swept up to eliminate overwintering eggs. The eggs are mostly concentrated on the underside of leaves and are yellow; before the 3rd instar they mostly cluster together, so promptly removing infested leaves can reduce the damage. For chemical control, 80% dichlorvos emulsion
at 1000 times dilution, or 50% phoxim emulsion at 3000 times dilution can be sprayed.
3) Willow thrips
Willow thrips are relatively common in Shandong, Jiangsu and Anhui, and are especially serious in dry autumns, often causing large patches of willow leaves to curl and shrivel, affecting the growth of Salix integra.
Willow thrips have multiple generations per year. Adults overwinter in fallen leaves and weeds, begin to be active in March and April of the following year, and reach their highest density in August and September. Eggs are laid within the vein tissue on the underside of leaves, one per site; after hatching they concentrate on the underside of leaves. For chemical control, 80% dichlorvos emulsion at 1000 times dilution or 50% phoxim emulsion at 500-1000 times dilution can be used, with spraying starting in late July.
4) Willow aphid
The willow aphid, also called aphid, commonly known as honey bug, has many species and is a common pest in willow fields, appearing multiple times a year, most commonly during the seedling stage in spring.
The reproduction of the willow aphid is related to temperature and humidity; both too dry and too waterlogged conditions favor reproduction. In China, depending on climate, it has 5-20 generations per year. In southern Shandong, the willow aphid generally has 4-6 generations per year, concentrated mainly in spring, causing serious damage. Generally, aphids require 4-17 days to complete one generation. They overwinter as wingless adult aphids and nymphs on weeds around the clumps. In mid-to-late March of the following year, they begin to reproduce. In mid-to-late April, when the temperature rises above 14°C, large numbers of winged aphids are produced that parasitize and reproduce in willow fields, mostly congregating on the terminal leaves or tender shoot tips of willow branches to pierce and suck sap. In severe cases they cover the leaves, causing the leaves to curl and growth to stop. Besides harming Salix integra, they also harm various trees and other crops.
For the control of the willow aphid, winter earthing-up in willow fields should be combined with the elimination of weeds and fallen leaves to destroy willow aphids on self-sown grass plants. Timely and generous watering to keep the soil moist and sticky can prevent willow aphid outbreaks. For biological control, the seven-spotted ladybird can be used; one seven-spotted ladybird can eat 270 aphids in a day and night, and one adult hoverfly can prey on 400. For chemical control, 40% dimethoate emulsion at 1000 to 1500 times dilution can be sprayed per mu, and spraying with 1605 solution is best.
5) Underground pests
In recent years, with the expansion of Salix integra planting area, new pests have continuously appeared, with underground pests being the most serious.
At present, in addition to common underground pests such as cutworms, ginger worms, and maggots in willow fields, the newly appearing weevil is the most harmful to Salix integra. The weevil parasitizes the roots of Salix integra. The roots of affected crops develop black spots, begin to rot and dry up, causing
Salix integra to die from lack of water. The weevil hatches into adults in March, lays eggs and enters the soil in November, feeding exclusively on crop roots. Active control is essential, otherwise Salix integra will die in large patches.
When underground pests occur, the most effective control method is root drenching, using pesticides such as methyl isothiophos or shennongdan funan, drenching the roots once each in early March and mid-July. First open a furrow, then apply the pesticide, and water after application. In plots with severe pest damage, the crop should be rotated; plant new shoots after 2-3 seasons, and apply sufficient pesticide before planting, which can also have a controlling effect.