Control methods for two common diseases of Anthurium
Symptom one: ring-shaped markings on the spathe. Cause: mild damage from Tomato spotted wilt virus. This symptom mostly occurs in summer. Generally, this virus does not pose a direct threat to the plant. It can be transmitted by thrips. When thrips larvae feed by piercing and sucking, they take the virus into their bodies, then pupate, and the adults transmit the virus. It has been observed
Symptom one: ring-shaped markings on the spathe
Cause: mild damage from Tomato spotted wilt virus. This symptom mostly occurs in summer. Generally, this virus does not pose a direct threat to the plant. It can be transmitted by thrips. When thrips larvae feed by piercing and sucking, they take the virus into their bodies, then pupate, and the adults transmit the virus. It has been observed that this virus cannot be transmitted mechanically.
Solution: Usually, thrips control methods are combined with preventive measure a (especially removing diseased plants and hosts from the greenhouse) to bring it under control.
Symptom two: petiole rot
Cause: Localized rotting of the petiole at the lower part of the leaf is caused by excessive root pressure due to high temperature and high humidity in summer. Under these environmental conditions, the leaves cannot evaporate enough water, the pressure from the roots increases, and the cells in the upper part of the petiole burst. After the cells burst, they cannot transport nutrients, causing the leaves to fade.
Solution: Adjust the temperature.
1. Red or scorched-red patches appear in the mesophyll of young leaves, with abnormal marginal wrinkling.
2. Copper-containing pesticides easily cause the spathe to fade and turn white.
3. Rust-colored red spots appear on the mesophyll of old leaves.
The following pesticides applied to Anthurium will cause phytotoxicity: diazinon, methamidophos, malathion, dimethoate, oxydemeton-methyl, acephate, dichlorvos, oxamyl, propoxur, parathion.
A. Bacterial blight (Xanthomonas campestris PV.)
Symptoms appear mainly on leaves and flowers, with brown spots in the center and yellow at the edges; water-soaked spots can be seen in the transition zone between uninfected and infected cells. Blight spreads extremely quickly and can cover most of the leaf. Sometimes blight can enter the cells and vascular bundles and be transported, thereby killing the whole plant (that is, systemic). Blight usually starts on leaves and flowers; cutting off the infected parts in time can prevent the infection from spreading through the plant tissue. There is no specific cure for bacterial blight; the treatment methods are:
1. Spray the seedbed regularly with streptomycin sulfate or oxytetracycline. Plants can also be sprayed with these agents (spray once every other week, with the concentration further diluted 6-8 times).
2. Remove or isolate infected plants.
3. Do not apply XH4 fertilizer; reduce the total x fertilization level.
B. Erwinia ((Erwinia)
Symptoms: leaves yellow, starting from the base of the petiole and rising along the main vein, with damage especially severe on seedlings. Control method: use streptomycin sulfate with an active ingredient of 4g/L, sprayed at 1.5 grams/100 liters of water.
C. Pseudomonas diseases (Pseudomonas)
Symptoms: necrotic disease appears along the leaf veins, sometimes with the veins as the boundary of the lesions; black spots usually have a very thin yellow halo. Control method: see blight control A.
D. Spot disease (Anthracnose, colletltrichem gloseosporioides)
Symptoms: under humid environmental conditions, it causes countless black spots on the leaves; under dry conditions, it causes light-colored spots when the leaf edges are moist. Both closely resemble the scorched spots caused by overly concentrated fertilizer, and similar symptoms easily appear on the leaf sheaths as well. On the bracts of the florets, spot disease causes countless small brown spots at the base of the bract. Be careful to distinguish anthracnose from spots burned by strong light. Control method: spray with benomyl, carbendazim, captan, chlorothalonil, zineb, etc. at 600-1000 times dilution.
E. Root rot (Pythium / Phytophthora)
Symptoms: root rot is a fungal disease triggered under unfavorable conditions such as overly dry, overly wet or overly cold substrate. The roots show localized rotting and death; the leaf edges turn yellow, the leaves become soft and droop, and some roots are brownish, while the inside of the roots remains unrotted. Root rot can be caused by Phytophthora, and it also damages stems and even leaves, causing brown and other discoloration. Agents such as furalaxyl, propamocarb hydrochloride, etridiazole and dimethomorph can be used.
F. Cylindrocarpon (Cylindrocarpon destructans)
Symptoms: leaves gradually dry out, showing yellowing, fading and wilting; the base of the plant turns brown, sometimes shrinks, and this fungus can penetrate from the stem base into the roots and cause continuous damage. The control method is drenching with the following agents: benomyl, thiophanate-methyl, carbendazim, etc.
G. Cylindrocladium (cylindrocladium Spp) Symptoms: this type of fungus infects the roots and base of the plant, appearing dark brown.
H. Fusarium (Fusarium SPP)
Symptoms: the base of the plant rots away. Fusarium is a secondary disease caused when environmental conditions are unsuitable for plant growth. After infection, continued invasion by Fusarium can subsequently be seen in the vascular bundles of the main stem. Control methods are the same as A.
I. Leaf spot disease (5eptorla anthuil Septoria)
Symptoms: brown leaf spots form, with dead centers surrounded by a ring of yellow tissue. Control methods: drench with captan, chlorothalonil, mancozeb.
J. Rhizoctonia (Rhizoctinia)
Symptoms: this type of fungus causes brown or black discoloration of the plant base and roots, and the damage mainly appears at the boundary between the substrate and the air. The control method is drenching with the following agents: benomyl, carbendazim, iprodione (Rovral), etridiazole, tolclofos-methyl.
K. Nematodes There are mainly three types: root-knot nematodes, lesion nematodes, and Pratylenchus.
The root-knot nematode genus MelOIDdogyne: after these nematodes invade, they cause poorer growth and swollen roots. The latter two also cause poorer plant growth, but brown patches appear on the roots rather than swelling. Inside these lesions are small nematodes, which quickly destroy and block the roots in that area, which in turn leads to secondary fungal infections and the formation of root rot. Control measures include:
1. Before planting, the growing substrate should be steam-sterilized, or a completely new growing substrate should be used.
2. Buy seedlings free of disease.
3. Keep the cultivation system off the ground.
4. Strict hygiene measures.
L. 1. Aphids
Symptoms: aphids themselves are light green, yellow or pink, have 6 legs, and are about 2mm long. Aphid populations develop very quickly because they reproduce by live birth, and they secrete honeydew, which triggers fungal growth. Aphids cause spots on flowers and leaves, thereby reducing commercial quality; they also suck the plant's sap and then inject toxic saliva into the plant tissue, affecting plant growth. Aphids have many plant hosts, causing rapid spread of disease. Control method: spray any one of the following agents, and spray again after five days: pirimicarb, heptenophos, bifenthrin, imidacloprid. Or use natural enemies for control.
M. Spider mites
Mainly (greenhouse) red spider mite and bean-shaped red spider mite (Tetranychus urtica).
Symptoms: spider mites (also called arachnid mites) are very tiny oval-shaped (elliptical), spider-like, white to green (sometimes brown to red) transparent insects that cause young leaves or buds to wilt. They penetrate plant cells and suck out the contents, causing the plant cells to turn silvery-white. Red spider mites appear on the old leaves of Anthurium, and severe damage causes the plant to yellow and fade. If they damage the spathe, small brown dots can be seen; if they develop to an extremely severe stage, spider mite webs can be seen on the plant. The control method is to use acaricides: dicofol, abamectin, omethoate, azocyclotin, amitraz (Mitac), azinphos-methyl, diazinon, pyridaben, bifenthrin, fenbutatin oxide, hexythiazox, and clofentezine.
N. Small mites (Mites)
Symptoms: mainly manifest as discoloration (fading) of leaves and flowers, lumpy tissue and deformation; these mites are invisible to the naked eye. For control methods, see the control methods for red spider mites above; the more broad-spectrum acaricides include Talsta, F01imat, Pentac and Kelthane).
O. Whitefly
There are mainly two types: greenhouse whitefly (Trialeurodes, Vaporariorum) and cotton or tobacco whitefly (Benisia tabaci). Damage symptoms: the insect is about 1mm long, and the adult's body has a waxy white powder, giving it a white appearance. Greenhouse whitefly most easily causes damage among weeds, while Benisia tabaci is the main whitefly damaging Anthurium. They suck the cell contents and dry them out, causing the leaves to discolor, and they secrete honeydew on the leaves, which in turn triggers the growth of black mold and further causes disease. Control pesticides: methomyl, abamectin, buprofezin, pyriproxyfen, fenbutatin oxide.
P. Snails and slugs
They chew the root tips and destroy leaves and young shoots. If there are many small blister-like spots on the leaves, it is usually snails that did it. Snails can be trapped and killed with beer or potato chips. Molluscicides include: methiocarb, snail pellets, or a half-and-half mixture of the two.
Q. Viruses
Potato spotted wilt virus. Symptoms: black necrotic dry spots appear, and the spots have a yellow ring, which is visible. This virus does not pose a major threat because the plant cells quickly encapsulate and isolate it. This virus is transmitted by thrips; thrips larvae acquire this virus during the larval stage, and after pupation the adult thrips transmit it to the plant. As far as is currently known, this virus is not mechanically transmitted. Control methods: there are very few effective controls for viruses; control must target the insect pests that transmit the virus, preventing thrips damage. Once viral infection appears, the only option is timely removal and isolation.
Source: China Flower and Tree Network