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Occurrence Patterns and Control Methods of Cotton Red Leaf and Stem Blight
Disease symptoms and occurrence patterns: Cotton red leaf and stem blight is an explosive disease that frequently occurs in the middle and late stages of cotton growth. It can cause leaves to turn red from bottom to top until they drop off. The leaf veins remain green, the leaf mesophyll turns red, and the leaves become thicker, brittle, and wilted before finally dropping. When the stem is cut open, it does not change color, which distinguishes it from cotton Fusarium and Verticillium wilt. Generally, in old cotton-growing areas, the disease is more severe in cotton fields with continuous cropping year after year, sandy soil, too shallow a plow layer, or insufficient fertilizer lacking potassium fertilizer. Drought in the middle and late stages, along with severe potassium and zinc deficiency in the soil, can also easily accelerate the occurrence of this disease.
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What to Do About Acute Bacterial Wilt in Cotton? Causes and Control Methods
Fusarium wilt symptoms in mature plants take several forms. Leaves may also show yellowing-type and net-vein-type patterns, and defoliation occurs easily. On severely affected plants, the top leaves are crinkled and deformed, dark green in color, with shortened internodes and a stunted plant form. After rain, an acute wilt type often appears, with the cotton plant suddenly losing water. The leaves wilt and turn green-wilted rapidly, droop, and often drop off leaving bare stems. Disease pattern: Cotton Fusarium wilt mainly overwinters in the seeds of diseased plants, diseased plant residues, soil and manure. The transport of infected seeds and infected oilseed cake fertilizer is the main cause of disease outbreaks in new areas. Cultivation and management in cotton fields of affected areas
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Symptom Identification and Control Methods for Cotton Angular Leaf Spot
Symptoms: This disease not only damages cotton seedlings but also harms the stems, leaves, and developing bolls of mature plants. When seedlings are infected, the cotyledons develop water-soaked irregular or round lesions that are dark brown; in severe cases, the cotyledons wither and drop off. When true leaves are infected, small dark green spots first appear on the underside of the leaves, then expand into oil-soaked lesions; on the upper surface of the leaves, the lesions are mostly angular, and sometimes the lesions extend along the veins in irregular streaks, causing the leaves to turn yellow and drop off. When stems are infected, water-soaked main lesions appear, then expand and turn black or rot, the diseased area becomes sunken, and the pathogen bends to one side. When the terminal bud is infected, it forms a "rotten top," causing the entire plant to die.
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Control Methods and Technical Key Points for Licorice Brown Spot Disease
Brown spot disease is an infection caused by a type of imperfect fungus (Deuteromycete), mainly damaging the leaves. Its symptoms are: circular or irregular lesions appear on the leaves, the center of the lesion is grayish-brown, the edge is brown, and black mold-like growth occurs on both sides of the lesion. Control methods: spray 1:1:100-1:1:160 Bordeaux mixture or spray 70% thiophanate-methyl wettable powder at 1500x-2000x dilution.
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How to prevent and control licorice rust? Detailed explanation of prevention and control methods
The pathogen is a basidiomycete fungus, mainly affecting the leaves. On the underside of infected leaves, yellow-brown blister-like lesions appear on one side; after the epidermis ruptures, brown powder is released, which are the uredinia and urediniospores of the pathogen. From August to September, dark brown teleutosori form. Prevention and control methods: 1. Collect diseased plant leaves and burn them. 2. At the early stage of disease onset, spray 0.3-0.4 degrees Baume lime sulfur mixture or 97% dithianon sodium 400-fold solution.
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Identification and control methods of the licorice seed weevil
Morphological characteristics: The adult is oval, brown or dark brown, with a body length of 2.5-3mm and a width of 1.5-1.8mm; the antennae are broad and short, serrate, and do not reach the base of the elytra. The pronotum is covered with punctures and dense light brown hairs, and its posterior margin is as wide as the elytra. The elytra are covered with punctures and dense light brown hairs. The pygidium is long, slightly pointed at the tip, and the ventral surface is covered with dense light brown hairs. The inner margin of the hind femur has 1 small, indistinct tubercle near the tip; the inner margin of the hind tibia has 1 long tooth at the tip; the first segment of the hind tarsus is the longest. Damaged crop: licorice. Damage symptoms: main
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Symptoms and Control Methods of Licorice Root Rot
Latin scientific name: Rhizoctonia solani Kuhn. Damage symptoms: Infected plants develop yellowed, withered leaves; the stem base and main root all turn reddish-brown and dry-rotted, with longitudinal cracks or red streaks on them; lateral roots are rotted or very few; diseased plants are easily pulled out of the soil; the vascular bundles of the main root turn brown; when humidity is high, pink mold grows on the roots. Morphological characteristics of the pathogen: generally caused by nematodes and Pythium species. Classification: called Rhizoctonia solani, a fungus of the subphylum Deuteromycotina. Disease occurrence characteristics: Fusarium is a soil-inhabiting fungus, in the soil
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Detailed Explanation of Control Methods for Licorice Leaf Spot Disease
① The pathogen is a type of imperfect fungus (Cercospora astragali), belonging to the subdivision Deuteromycotina → Moniliales → Cercospora fungus. It damages leaves; affected leaves produce circular or irregular lesions, with the center of the lesion grayish-brown and the edges brown, and grayish-black mold-like growth on both the front and back of the lesions. Fruiting bodies grow on both sides of the leaf, but mainly on the upper surface; the stroma consists of only a few brown cells; conidiophores are born in bundles of 6 to 12, pale brown, with the apex lighter in color and narrower, unbranched, having 0 to 5 geniculate nodes, with the apex nearly truncate, spore scars prominent, and 1 to 7 septa; conidia are whip-shaped to obclavate, colorless and transparent, straight to curved, with the base truncate to nearly truncate, the apex slightly blunt, and 3 to 10 septa.
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Symptom Characteristics, Causes, and Control Methods of Oleander Witches' Broom
The oleander witches' broom pathogen mainly attacks oleander branches. The disease initially occurs mostly on individual branches, showing mass sprouting of axillary buds and adventitious buds, with many slender weak branchlets growing in clusters, stagnation of main shoot growth, shortened internodes of branchlets, and smaller leaves with indistinct mosaic patterns. Infected branchlets can produce further branchlets, and the bases of newly sprouted branchlets are swollen, pale red, and often clustered in groups. The branchlets become increasingly slender and weak, and the leaves become increasingly smaller, resembling a bird's nest in appearance, forming the typical witches' broom symptom. Most affected branchlets stand upright, and the branches have tumor-like growths. The cortex rots and peels off in strips, forming cankers,
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Pollution-free control methods for pests and diseases in flowers, trees and bonsai
Alcohol swabbing method: gently swab the leaves of orchids infested with scale insects using disinfecting alcohol; this can kill the scale insects, and in the following year there will rarely be any scale insect damage. Vinegar swabbing method: soak a cotton ball in edible vinegar (rice vinegar), then gently swab the leaves of camellias; this not only kills scale insects but also restores the damaged leaves to a green, glossy condition. Iodine swabbing method: when dry rot is found on the trunk of a stump bonsai, immediately use a blade wiped with iodine to scrape away all the rotted parts, reaching down to the xylem, then apply iodine to the main trunk; one week
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