Bacterial canker of tomato

strong efforts are used to prevent the bacterium from entering. When the occasional infection is found, strict measures are taken to eradicate the infection [...] Replanting can only take place after thorough disinfection has been proven to the authorities. Potato growers lose their entire crop of the affected field [...] On stems and shoots light stripes form, which then tear, allowing cankers to form. On tomato leaves, water-soaked lesions occur, usually white with a brown

Damping-off

spores with flagellae, which enable the spores to move through water. The zoospores are chemically drawn to the growing roots of young plants and move towards [...] plant, new sporangia with zoospores are formed, that allow the disease to spread to neighbouring plants. The zoospores disperse via water. Therefore, this [...] with a finger nail. Life cycle and appearance of Damping-off Pythium belongs to the Oomycetes, a separate group of microorganisms and is therefore not a real

Phytophthora blight

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 [...] wetness is required. Dispersal is by wind and rain causes the pathogen to be returned to the soil from infected plants. Dispersal in the soil happens via water [...] Phytophthora blight Phytophthora species are very destructive organisms belonging to the Oomycetes and are therefore strictly speaking not fungi. They thrive at

Angular leaf spot

causes small, water-soaked lesions on the underside of the leaf. They enlarge to angular spots, often limited by the small veins. The distinctive feature is [...] bacterial exudate forms on the underside of the leaf. This exudate changes to a white film when it dries. Lesions may merge as they grow and later also [...] types of vascular tissue of the crown can be infected, creating a look similar to that of a Phytophthora fragariae infection. Life cycle and appearance of Angular

Southern blight

the stand, meaning it is very often necessary to replant, which increases the crop's production costs. How to prevent southern blight Life cycle and appearance [...] in Florida in 1892, and it has been regularly reported as causing rotting to the root and stem in tomato plants. Significant losses occur in soils infested [...] infested by the pathogen, which have a light texture and humidity close to field capacity. In the southern USA, losses can reach 5% of annual production.

Grape downy mildew

instead of overhead irrigation to reduce leaf wetness. Ploughing to bury oospores in leaf litter and avoiding prolonged irrigation to prevent oospore germination [...] ‘oilspots’ with a chocolate-brown halo. On older leaves: small, angular, yellow to reddish-brown spots forming a mosaic-like pattern. Sporulation occurs on the [...] seasons in typically dry areas. Most grape cultivars are highly susceptible to downy mildew. Breeding programs started in the 1930s and have focused on

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

Black root rot of cucurbits

‘clean’ or sterilized soil and substrate. It aggregates, so disinfection needs to be applied thoroughly and evenly. Phomopsis sclerotioides forms sclerotia [...] The lesions may grow and encircle the root. The roots become yellow-brown to black and ultimately die. Black lesions with fruiting bodies occur more commonly [...] coloured tissue that looks like black stripes. The disease is usually restricted to a few of the roots but in severe cases all roots may be infected. At the final

Bacterial spot

and handling and aerosols. Many isolates are resistant to copper-containing pesticides. How to prevent Bacterial spot Use clean propagation material and [...] surrounded by a halo. In pepper, the spots on the leaves are also round and small to start with and slightly raised from the leaf surface. They occur on the abaxial [...] is favoured by temperatures between 24 and 30 °C and high precipitation due to rain, fog or overhead irrigation. Infection is through stomata and wounds

Downy mildew of Cucurbits

mildew Pathogens causing downy mildew are not fungi but Oomycetes and related to Pythium and Phytophthora. They survive as oospores. From these oospores 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 [...] can take up nutrients from the living plant cells. The pathogens continue to grow inside the leaves and after a while new spore-bearing structures are