Downy mildew of Cucurbits

downy mildews, 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 [...] yellow and then turn brown. On the underside of the leave fluffy growth appears which is first white and later turns grey-brown. This is actually the sporulation [...] directly and the germ tubes infect the plants either through the stomata or directly by penetrating the cuticula. For germination free water is required

Bacterial wilt, brown rot

s roots on the stem. The vascular stem tissue is coloured brown and when the stem is cut, bacterial slime oozes from the wound. This is the way to distinguish [...] st organism in the United States. It is a commonly found soil-inhabitant in tropical and subtropical regions and is transferred by the introduction of [...] Ralstonia solanacearum is a plant pathogenic bacterium. It is a soil-borne disease and colonises the xylem, causing bacterial wilt and brown rot in a very

Fusarium wilt

may occur and cause different symptoms. Fusarium oxysporum is the only Fusarium that actually grows inside the vessel system of the host plant and spreads [...] blight in cereals and post-harvest decay. Fusarium oxysporum is the species causing vascular wilt. First the leaves turn yellow and wilt, mostly on one [...] one side of the plant. Finally, the whole plant wilts. Other symptoms are brown discolouration of the xylem vessels which can be seen when the stems are

Black root rot of cucurbits

roots. The lesions are slightly sunken and are mostly formed around the point of attachment of lateral roots and root hairs. The lesions may grow and encircle [...] about the life cycle. The fungus is dispersed by water, air and soil particles. How to prevent Black root rot of cucurbits Test for the presence of Phomopsis [...] 10 °C the lesions are light-brown. The lesions can be enclosed by pseudostromata: dark coloured tissue that looks like black stripes. The disease is usually

Leaf stripe

formed at the base of the leaf and the leaf sheath. They gradually extend and become brown and chlorotic and may merge. Eventually this leads to the death [...] fungus is seed-borne and this systemic infection is the only source of primary infection. The fungus spreads from the seed into the seedling. Conidia are produced [...] be distorted and failing to emerge from the sheath. Ear length and the number of kernels may be reduced and kernels may be brown. The symptoms do not always

Pierce's disease of grapevine

(peaches and plums): In peach, the canopy of infected plants is compact and umbrella-like due to the shorter internodes. The foliage is denser and the leaves [...] along the margin or the tip from early to midsummer. The necrotic area spreads over the leaf from the margin and is marked by a chlorotic band. In the beginning [...] normal and look stunted. Twigs and branches die and the foliage becomes thinner, but the trees don’t die of the disease. Olives: Scorch symptoms and desiccation

Bacterial soft rot, bacterial stem rot

rot is first noticed when plants wilt at the time of first harvest or after that. The pith disintegrates and the stem becomes hollow. Because of the bacterial [...] bacterial growth in the pith, the stem seems wet and slimy. Above or below the hollow stem the vascular tissue keeps its normal colour. On the fruits, lesions [...] first are small and sunken, water-soaked and light to dark brown. They are adjacent to wounds and natural openings at the stem end. Later the fruit becomes

Monitoring

Angular leaf spot

underside of the leaf. They enlarge to angular spots, often limited by the small veins. The distinctive feature is the way the lesions look when using different [...] visible on the upper side of the leaf as irregular spots which are first reddish brown and then become necrotic. The foliar symptoms are the most important [...] Infection of the plants happens both passively and actively. Infection and disease development are favoured by temperatures around 20 °C during the day and cold

Fusarium head blight or scab

doesn’t germinate well and seedlings die, causing irregular crop density. The foot of the plant is infected, either because the seedling was infected or [...] primarily infects the older, lower leaves. The spores are dispersed upwards to the ears by splashing rain drops or wind. On the infected ears, the typical pink [...] greenhouse structures, tools and machinery. Primary infection is either seed-borne or takes place as infection of the roots at the root tip or in small wounds