Black sigatoka disease

one month old. The symptoms run parallel to the veins. Within a few days, the spots become a few centimetres in size and turn brown with light grey centres [...] three days under optimal conditions (humidity close to saturation and temperature above 20 °C). How to prevent Black sigatoka disease Use resistant cultivars [...] spores cannot be discharged from the lower leaves in the stack Use under-canopy (drip) irrigation to reduce splash dispersal Lower the humidity as much

Grapevine powdery mildew

mildew vary according to the phenological growth stage and the severity of the infection. Early signs manifest as chlorotic (pale green to yellow) spots, which [...] the characteristic white to grey powdery mycelium. As the infection intensifies, affected leaves suffer a marked reduction in photosynthetic capacity, [...] the pathogen colonizes the epidermis, causing the skin to lose elasticity. This frequently leads to berry cracking, which severely compromises fruit quality

Pea blight, leaf and pod spot

) causes foot rot in peas, whereas Ascochyta pisi does occur sometimes at the stem base but is not part of the foot rot syndrome in peas. Infected seeds [...] and the spores require water for dispersal. How to prevent Pea blight, leaf and pod spot Grow peas in arid regions Use clean seed Use a minimum crop rotation [...] elongated. The lesions are light brown, sunken and surrounded by a dark brown to red-brown border. The first infection is often on the primary leaves. The

Phytophthora blight

optimal for crop growth. Phytophthora overwinters in roots, infected tubers and bulbs or in the soil in different stages: as oospores (sexual overwintering [...] Zoospores are spores with flagellae which enable them to move through water. Infection is usually from the root to the foot, but direct infection of the foot also [...] produced in the sporangia. For germination on above-ground plant parts, leaf wetness is required. Dispersal is by wind and rain causes the pathogen to be returned

Downy mildew of Cucurbits

and related to Pythium and Phytophthora. They survive as oospores. From these oospores or surviving mycelium sporangia are formed, structures in which zoospores [...] zoospores are produced. However, in downy mildews, sporangia often germinate directly and the germ tubes infect the plants either through the stomata or [...] the optimum temperature is around 15 o C and the closer the temperature is to this, the shorter the leaf wetness period that is required. Inside the plant

Leaf stripe

soil temperatures above 15 °C. How to prevent Leaf stripe Produce seed in semi-arid environments without irrigation, to decrease the chances of infection [...] extend and become brown and chlorotic and may merge. Eventually this leads to the death of the leaf. The leaf splits at the end which makes it look shredded [...] disease. Infected plants may be stunted and heads may be distorted and failing to emerge from the sheath. Ear length and the number of kernels may be reduced

Loose smut of barley

Infection mostly occurs before pollination and within one to two days after pollination. How to prevent Loose smut of barley Use clean seed: Apply systemic [...] during flowering and the infected seeds are the primary source of inoculum in the next crop. The fungus survives inside the seed and when the seed germinates

Loose smut of wheat

Infection mostly occurs before pollination and within one to two days after pollination. How to prevent Loose smut of wheat Use clean seed: Apply systemic [...] during flowering and the infected seeds are the primary source of inoculum in the next crop. The fungus survives inside the seed and when the seed germinates

Melon thrips

Mated female lays 3 to 204 eggs. Eggs are deposited in leaf tissue in a slit cut by female. Eggs are colourless to pale white in colour. The nymphs resemble [...] drops to soil and pupate in soil. There are two pupal stages viz., prepupae and pupae. Adults are pale yellow or white in colour and 0.8 to 1mm in length [...] feed on leaves, less damage to buds and flowers. In addition to direct damage, it also transmits virus from infected to healthy plants. Life cycle and

Precautionary measures for product allergies

Just as you can be allergic to cats, pollen, and dust mites, it is also possible to be allergic to the natural substances in predatory mites , feeder mites [...] taken to prevent possible allergic reactions. Exposure and precautionary measures Depending on the way in which you are exposed to the substances in these [...] or could take years to appear. Not everyone who is exposed to allergens will develop an allergy. It is difficult to determine in practice which substance