The leaf curl disease of cotton crops is primarily managed by the use of pesticide treatments; often frequent, to kill the whitefly vector to reduce virus transmission by the vector. The lack of alternative control options has led to the profuse, and often overuse, of pesticides to reduce vector populations.
Recommendations for CLCuV management include cultivating resistant cultivars, destruction of alternate hosts; uprooting and destruction of infected plants; avoidance of upland cotton in orchards; effective management of whitefly and avoidance of insecticides that cause resistance in whitefly.
Leaf curl can usually be controlled satisfactorily by a spray of a suitable registered fungicide at any stage of dormancy. Most effective control is achieved by spraying when the buds are swelling but before they have opened. It's not possible to control the fungus once it's entered the leaf.
Apply Carbofuran 3G @ 4-5 Kg/acre in the mainfield to control sucking complex and insect vectors selectively. If it is not possible spray the crop with systemic insecticides. Dimethoate 2ml of Acephate 1g per litre of water. Collect and destroy infected virus plants as soon as they are noticed.
Cotton leaf curl disease (CLCuD) is a viral infection of cotton and other susceptible host plants that is transmitted by silverleaf whitefly (Bemisia tabaci). There are a number of different cotton leaf curl viruses (Begomovirus species) associated with CLCuD.
Organic Control Methods for Leaf Curl
Spray at bud-swell with copper hydroxide or copper oxychloride and ensure thorough coverage over all branches. Timing is critical to prevent the fungus entering the plant when new leaves are vulnerable.
Leaf curl disease shows up in spring, does the damage, and then disappears (until next spring). If your trees were infected last spring, they should have completely recovered by mid to late summer. They usually grow lots of healthy new leaves (like the photo below).
Best Treatment for Leaf Curl
Where Leaf Curl has been severe in the previous year, trees can also be sprayed with Yates Liquid Copper Fungicide in autumn when the leaves drop, plus at the first sign of bud swell and again one week later.
Leaf curl starts appearing in early spring on stone fruit trees. Spray a mixture of apple cider vinegar and water in winter and early spring when buds appear, then every couple of weeks. This will help with brown rot, black spot and leaf curl, to name a few.
To prevent peach leaf curl, treat susceptible trees with a preventive fungicide every year after leaves fall. Treating after symptoms appear won't be effective. When planting, consider tree varieties resistant to the disease.
Several other fungicides that are equivalent or even more effective than copper for managing peach leaf curl are ziram, chlorothalonil (Echo or Bravo), and dodine (Syllit) when applied at the optimal time. Ziram is most effective.
The Leaves Are Curling Over
But even though they're known to do this (and many other plants too), sometimes it's a sign that they're being over-watered. Overwatering causes the leaves to curl up at the tips and edges, as seen here.
Spraying in winter and again in early spring is your best bet of keeping the fungus at bay. Organic approved sprays such as Neem Oil, Horticultural Oil, Bi-Carb and Copper all work but we've found Copper to be by far the most effective against leaf curl.
To control leaf curl, spray with PLANThealth Copper Fungicide soon after pruning, just before bud burst happens in Spring. Disease is often carried between plants by sap sucking insects. Use Organic Super Spraying Oil to control these insects before they can spread disease.
The leaf roller is usually controlled by natural enemies , particularly parasitic wasps, spiders and praying mantis. Removal and destruction of eggs, caterpillars, pupae and rolled leaves help to reduce damage.
Prevent Leaf Curling
Another sign of magnesium deficiency, this problem can also be tackled with the help of Epsom Salt. Mix two table spoons in a gallon of water and spray your curled foliage with the solution until the leaves look perfect again.
Apple Cider Vinegar
To make a natural fungicide out of this, take one tablespoon of vinegar and mix it with a gallon of water. Shake it well and add to a spray bottle. A vinegar mixture can treat most fungal infections on any plant without causing any harm.
The leaves eventually turn yellow and drop off. Healthy new leaves do emerge to replace the fallen ones unless subsequent spring showers cause the disease to spread to the new leaves.
It is recommended to treat the trees just after most of leaves have fallen, usually late November or December.
Leaf curl can be controlled by applying sulfur or copper-based fungicides that are labeled for use on peaches and nectarines. Spray the entire tree after 90% of the leaves have dropped in the fall and again in the early spring, just before the buds open.
Over-watering.
Overdoing your watering can have a similar effect to underwatering. You may also find your plants produce an excess of foliage but few tomatoes. Leaves might yellow and wither, or they could curl.