Cotton blue disease, also known as cotton leafroll disease, is caused by Cotton leafroll dwarf virus and can result in severe stunting of cotton plants. The virus is transmitted between susceptible cotton varieties by cotton aphid (Aphis gossypii).
Foliar leaf spots (bacterial and fungal), boll rot and cotton leaf curl virus disease have been considered important diseases in Bt cotton and categorized into different cotton growing zones. Corynespora leaf spot, Grey mildew, and internal boll rot are emerging diseases in central and south cotton-growing zones.
Byssinosis. Byssinosis is a disease of the lungs. It is caused by breathing in (inhaling) cotton dust or dusts from other vegetable fibers such as flax, hemp, or sisal while at work.
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.
The cotton aphid is a vector for more than 50 plant viruses including potato virus, citrus tristeza virus, cucumber mosaic virus, and turnip mosaic virus (2–4). The host range for the cotton aphid includes more than 50 plant families including Asteraceae, Cucurbitaceae, Rosaceae, and Solanaceae (5–7).
Although large infestations of aphids have been reported to trigger allergic inhalant reactions in some people, these insects generally pose no threat to humans. It's largely due to the damage that aphids do to cultivated plants, especially in temperate areas, that they're regarded as pests.
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.
Peach Leaf Curl will cause the leaves to fall off and the fruit production of the tree can be affected. However, gardeners are usually relieved to hear that this disease rarely kills trees and can be easily managed if treated with a fungicide during the dormant season.
Bean thrips feed on the cotton plant and may cause mature leaves to turn coppery brown or red and lower leaves to drop. Bean thrips injury may resemble spider mite injury, but affected leaves are covered with tiny black specks, which are the feces of the thrips. Usually injury is confined to field borders.
The major health problems associated with cotton dust are respiratory problems, byssinosis, bronchitis and asthma.
Bagassosis is an airborne disease caused by inhalation of the fibrous cane-sugar residue, bagasse.[7] Chemically, bagasse is comprised of approximately 4% ash and 2% protein; the rest of the portion is made up of cellulose and various other complex plant carbohydrates.
One such condition is byssinosis, a collection of respiratory symptoms elicited by exposure to raw, nonsynthetic textiles during their manufacturing process. Over the years, byssinosis has been referred to as cotton worker's lung, brown lung disease, Monday fever, and mill fever.
Cracking of the stem and gummosis is also observed in infected plants. The resultant breaking of the stem which hang typically as a dry black twig is referred to as the 'black arm'. The pathogen also reportedly causes blackening of the veins and veinlets, giving a typical 'blighting' appearance.
Boll weevil (Anthonomus grandis) and pink bollworm (Pectinophora gossypiella) are serious cotton pests. For much of the 20th century, they caused tens of millions of dollars in damage to cotton producers, reduced land values, and greatly disrupted local economies.
Symptoms of 'tirak' include yellowing and reddening of leaves followed by bad opening of bolls. Educating farmers, he said that the 'tirak' appears when cotton suffers from persistent drought, nutrient deficiency on light sandy soil, inadequate water supply and too early sowing.
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.
Controlling the Spread of Peach Leaf Curl
Manually removing the infected leaves from the tree can help control the spread of Peach Leaf Curl. The discarded leaves contain fungus spores that can overwinter in the soil beneath the tree and reactivate in the spring.
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 very characteristic symptoms include leaf curling, darkened veins, vein swelling and enations that frequently develop into cup-shaped, leaf-like structures on the undersides of leaves.
The most organic method of control, and often a quite effective one, is the spray of water. Soapy water can help kill the aphids, as it sounds like you know, but a particularly strong jet of water will dislodge/kill most of them physically, as well.
Components of neem oil can be found in many products today. These include toothpaste, cosmetics, soaps, and pet shampoos. Neem oil is a mixture of components. Azadirachtin is the most active component for repelling and killing pests and can be extracted from neem oil.