Detailed Explanation of the Damage Symptoms and Control Methods of Fusarium Wilt
Fusarium wilt, also called blight, is a plant disease caused by fungi or bacteria. It strikes suddenly, and symptoms include severe spotting, wilting, or the death of leaves, flowers, fruits, stems, or the entire plant. Fast-growing young tender tissues are often attacked, and most major economic crops are infected by one or more types of blight. Let's take a look below at the control methods for Fusarium wilt!
Symptoms of Fusarium Wilt
After young plants are infected, they grow poorly. The leaves of diseased seedlings turn pale, with no obvious symptoms at first. In severe cases, the petiole bends down near the leaf sheath, then withers and dies, and afterward the stem wilts and dies. Finally, the diseased roots turn brown and rot, the stem base splits lengthwise, and cutting the stem open reveals browning of the vascular bundles. In mature plants, the old leaves turn yellow, accompanied by loss of green in the vascular bundles of the outer leaf sheaths. The yellowing starts from the leaf margin and then gradually spreads toward the midrib; some leaves turn entirely yellow. A pink mold layer, namely the pathogen's conidiophores and conidia, forms on the surface of the diseased parts. Finally, the diseased roots turn brown and rot, the stem base splits lengthwise, and cutting the stem open reveals browning of the vascular bundles.
The Occurrence Pattern of Fusarium Wilt
The pathogen mainly overwinters as mycelium, chlamydospores, or sclerotia in undecomposed organic fertilizer or soil, and can survive in soil for 6 to 10 years. The pathogen can spread through seeds, fertilizer, soil, and irrigation water, with compost and manure spreading being the main route. The occurrence of this disease is closely related to temperature and humidity. The pathogen grows at temperatures of 5 to 35°C, and a soil temperature of 24 to 30°C is suitable for its germination and growth. This disease is a soil-borne disease, and the degree of incidence depends on the amount of infective inoculum in the soil. Generally, continuous cropping, many underground pests, extensive management, or heavy, moist soil lead to severe occurrence of the disease.
Preventive Measures for Fusarium Wilt
1. Irrigation prevention: Dilute 41% polyene · pyrimethanil at 600 to 800 times with water, and irrigate the seedbed before sowing or after sowing and before planting, before 10 a.m. or after 5 p.m.
2. Root drenching prevention: At planting time or after planting and before the expected period of frequent disease occurrence, dilute 41% polyene · pyrimethanil at 800 times with water for root drenching, applying once every 7 days, with the number of applications depending on the condition of the disease.
Treatment Methods for Fusarium Wilt
1. Foliar spraying: Dilute 41% polyene · pyrimethanil at 600 to 800 times with water and spray evenly; when the disease is severe, the dosage may be appropriately increased.
2. Root drenching treatment: For diseased plants, dilute at 600 to 800 times for root drenching. If the pathogen also harms the aboveground parts, while drenching the roots, spray the aboveground parts at the same time, applying about once every 7 days.
Damage Symptoms and Control Methods of Plant Brown Spot Disease (Pictures)
Brown patch disease is a fungal disease caused by Rhizoctonia solani. It is widely distributed around the world and can infect all turfgrasses, with cool-season turfgrasses suffering the most severe damage, causing turf plants to die and forming large areas of bare patches in the lawn, greatly damaging the lawn landscape. Let's take a look below at what chemicals to use to control brown patch disease!
Turf Brown Patch Disease
[Symptoms] When the disease begins on turf, nearly circular patches of dead grass of varying sizes often appear. When conditions are suitable, the disease develops very quickly, and the diameter of the dead grass patches can expand from a few centimeters to one or two meters. Because the diseased plants at the center of the patch can recover, the dead grass patches mostly appear in a “frog-eye” shape, that is, green in the center with a withered-yellow ring at the edge.
[Control] Before or during hot and humid weather, apply little or no nitrogen fertilizer, maintain a certain amount of phosphorus and potassium fertilizer, avoid continuous flooding irrigation and broadcast irrigation, and especially avoid watering in the evening. When dead patches appear on the lawn, remove guttation (or dew) as early as possible in the morning, which helps reduce the severity of the disease. Do not mow too low in summer (generally 5 to 6 cm). For overly dense lawns, appropriately aerate and rake the grass. Remove dead grass and clippings promptly. Disease-resistant (tolerant) varieties should be planted, and timely and effective chemical control should be carried out.
Poinsettia Brown Spot Disease
[Symptoms] It damages leaves. At first there are small yellow-brown spots, sometimes dozens of spots on a single leaf. The small spots gradually expand into lesions 1 to 2 cm in diameter, light brown inside with slightly angular concentric rings of varying shades around the edge. In severe cases, the lesions can reach 2 to 3 cm in diameter. In the dark gray area where diseased and healthy tissue meet, gray-white cottony mold develops.
[Control] Thoroughly remove diseased residues to reduce the source of initial infection. Manage temperature and humidity well in the greenhouse, pay attention to ventilation and dehumidification, and improve air circulation and breathability.
Tulip Brown Spot Disease
[Symptoms] Infected leaf buds develop poorly and become deformed and curled; leaves that grow from damaged young buds become curled. If the environment is humid, a large amount of gray mold-like conidia forms on the diseased tissue, affecting neighboring healthy plants and causing leaf infection, so bulb growth is greatly affected. After flowers are damaged, white or light yellow-brown lesions appear at first, then rapidly expand and cause the flowers to wither and drop, or turn brown and dry up. Ring-like bands also appear on the flower stalk, where a layer of conidia sometimes develops.
[Control] Remove diseased bulbs before planting and practice crop rotation. Once buds or flower buds showing symptoms of this disease are found, remove them immediately to control the spread of the disease. Before planting, soak the bulbs in 2% formalin solution for 30 minutes, then dry and plant to reduce residual pathogens. During the growing period, spray 50% iprodione 1000 times, or 50% procymidone 2000 times, or 50% dimethirimol 1000 times.
Osmanthus Brown Spot Disease
[Symptoms] It occurs from April to October, with severe incidence in rainy seasons and years, and spreads fastest from July to August. Old leaves are more severely affected than tender leaves, and weak-growing plants and plants transplanted in the same year are prone to the disease. Different varieties of osmanthus differ in their resistance to brown spot disease; Dan Gui varieties have stronger disease resistance than Jin Gui and Yin Gui varieties.
[Control] When nursery stock leaves the nursery, remove diseased leaves and spray potassium permanganate 1000 times for disinfection. Select disease-free plants as mother plants for propagation. Strengthen cultivation management, combine canopy shaping with pruning of weak and diseased branches, adjust the density of branches and leaves, and enhance tree vigor. In the growing season, at the early stage of disease, spray the whole tree for protection, such as 70% copper hydroxide 300 to 500 times, azoxystrobin 1000 to 1500 times, or 50% carbendazim 500 to 600 times.
Impatiens Brown Spot Disease
[Symptoms] Impatiens brown spot disease, also called impatiens leaf spot disease, occurs in both northern and southern parts of China. The disease mainly occurs on leaves. Leaf lesions initially appear as small light yellow-brown spots, then expand into circular or oval shapes, and later the center becomes light brown with brown edges and inconspicuous concentric rings. On severely infected leaves, the lesions join together, causing the leaves to turn brown and withered yellow until the plant dies.
[Control] Impatiens likes fertile sandy loam and is not tolerant of waterlogging. Therefore, planting in sandy loam is preferable to facilitate drainage. For potted impatiens, repot promptly after rain. In late autumn, diseased leaves and diseased plants should be collected and destroyed to reduce the source of infection for the next year. At the early stage of disease, use 25% carbendazim wettable powder 300 to 600 times, or 50% thiophanate-methyl 1000 times, or 75% chlorothalonil 1000 times for control.
Morning Glory Brown Spot Disease
[Symptoms] Leaf lesions are scattered between veins and along leaf margins, nearly circular to polygonal, 2 to 6 mm in diameter, brown, or with a dark gray center and dark brown edge. A light black mold layer forms on the surface of the lesions. In severe cases, the lesions cover the entire leaf, and the leaves wither early.
[Control] Plant at an appropriate density, avoid excessive watering, and spray 7500 times of plant growth essence to promote early and rapid growth of plants. Spray 75% chlorothalonil wettable powder 1000 times plus 70% thiophanate-methyl wettable powder 1000 times, or 40% carbendazim suspension concentrate 600 times, or 50% procymidone wettable powder 2000 times, once every 7 to 10 days, for 2 to 3 consecutive applications.
Aster Brown Spot Disease
[Symptoms] Aster brown spot disease is a common leaf disease of aster. In severe cases, the leaves turn withered yellow, causing the whole plant to wilt. At first, nearly circular purple-brown lesions of varying sizes appear on the leaves, then turn black or black-brown. Later, the center of the lesions turns light gray and fine small black dots appear. When there are many lesions on a leaf, the entire leaf turns yellow and dries up. It generally starts from the lower leaves and withers upward in sequence.
[Control] Choose well-drained sites for planting. Planting density should be appropriate. Choose disease-resistant varieties. Remove diseased leaves immediately when found. In late autumn, collect diseased fallen leaves and diseased residues and destroy them centrally. Spray 50% carbendazim wettable powder 1000 times, or 80% zineb wettable powder 500 to 700 times, or 1% Bordeaux mixture, or 75% chlorothalonil 500 times for control. Spray once every 7 to 10 days.
Symptoms and Control Methods of Safflower Fusarium Wilt
Safflower is a medicinal plant with high medicinal value. In medicine, it has effects such as promoting blood circulation and regulating menstruation, and dispersing blood stasis and relieving pain. The site of safflower Fusarium wilt infection is the vascular bundles. At the early stage of the disease, the leaves of the plant turn yellow from bottom to top, the tips wilt, and sometimes half-yellowing and shrinkage occur. Below, the editor will introduce the symptoms and control methods of safflower Fusarium wilt.
Symptoms of Safflower Fusarium Wilt:
The lower leaves of affected plants begin to turn yellow, then gradually wither, and old plants die entirely. If one side of the plant is infected, that side dies. Seedlings are especially severely affected; the roots of affected seedlings become black-brown and thinner.
Pathogen of Safflower Fusarium Wilt:
The pathogen is Fusarium oxysporum f. sp. carthami Klisiewicz & Houston (FsariumOxysporumSchlechtft.spCarthamiKlisetHoust), a fungus of the genus Fusarium in the subphylum Deuteromycotina.
Occurrence Pattern of Safflower Fusarium Wilt:
The pathogen spreads from the roots through the vascular bundle tissue to the stems, branches, and leaves, causing the vascular bundle tissue of the roots and stems to turn yellow-brown. This fungus parasitizes in soil and on safflower residues, and spreads through the seed shell and the internal tissues of the seed coat. The disease occurs easily in acidic soil, under high nitrogen content, and in warm, humid climates.
Control Measures for Safflower Fusarium Wilt:
First, adopt rotation cultivation; second, do not use pathogen-carrying seeds; third, at the early stage of disease, promptly pull out diseased plants and burn them centrally, and spread quicklime in the disease holes and surrounding soil. You can also spray 50% carbendazim wettable powder 600-800 times, or 10% shuangxiaoling aqueous solution 200-300 times.
These are the symptoms and control methods of safflower Fusarium wilt compiled by the editor. The knowledge compiled by the editor is very helpful for you in growing your safflower. Everyone can study it carefully to reduce the damage your safflower suffers.