Downy mildew of rose

the foot is infected first and this causes the plant to fall over. In cabbage the stem is also infected in severe epidemics. In blackberry, red stripes may [...] appears which is first white and later turns grey-brown. This is, in fact, the sporulation of the pathogens extruding from the stomata. In lettuce, the [...] and sporulation is relatively low, in general between 10 and 20 °C. Late in the season new overwintering oospores are produced and buried in the soil with

Angular leaf spot

overwinters in plants and dead leaves, that become the primary source of infection in the spring. The bacteria are also introduced in a crop in new transplants [...] . This bacterium is very resistant to desiccation and can survive well in dry leaves or leaves in the soil, but not independantly in the soil. Under humid [...] nights, in combination with high humidity or presence of water. These conditions occur mostly in the spring if it rains or when sprinkler irrigation is used

Fusarium wilt

clean substrate in greenhouse crops Disinfect tools, machinery and irrigation water in greenhouses Prevent stress for the plants Ensure there is adequate soil [...] General Fusarium is a group of soil-borne fungi with many different species. Fusarium is widespread and can infect a range of host crops. Many species [...] stem rot, leaf lesions, fruit rot, head blight in cereals and post-harvest decay. Fusarium oxysporum is the species causing vascular wilt. First the leaves

False codling moth

codling moth ( Thaumatotibia leucotreta ) is native to sub-Saharan Africa and is found in all citrus production areas in Southern Africa. It also occurs on some [...] pest’s high pest status is its quarantine status and is not due to the economic losses. Damage and symptoms Larval penetration holes in the fruit can only be [...] thorough inspection. In green citrus fruit the peel around the penetration hole eventually assumes a yellow colour. On ripe fruit this area is orange, but eventually

Bacterial soft rot, bacterial stem rot

carovora is very common, but does not often reach epidemic population densities. It can survive as epiphytic bacteria on various plants or in the soil in low [...] found as secondary pathogen in plants that are infected by other pathogens. The bacteria that causes black leg in potato is a different subspecies. How [...] carotovora . It is one of the pectolytic bacteria causing extensive bacterial rots (bacterial soft rot, bacterial stem rot). Damage symptoms In tomato, Erwinia

Botrytis

Botryotinia fuckeliana / Botrytis cinerea ) is a commonly found fungus in many environments. It survives in plant parts like bulbs and crop residues or [...] much vegetative growth, in order to maintain a microclimate which is not humid enough for grey mould Provide sufficient ventilation in greenhouse crops Remove [...] plants or plant parts in a closed plastic bag In tomato: prune with a knife and not by hand, to avoid rugged, irregular wound surfaces In cucumber: remove dead

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 [...] dark brown to red-brown border. The first infection is often on the primary leaves. The fungus is seed borne and thus also causes post- and pre-emergence [...] survives in the soil or on crop residues because of its poor saprophytic competitiveness and because chlamydospores are rare. Primary infection is purely

Damping-off

aphanidermatum mostly occurs in young plants and damage is more extensive in young crops. Damage symptoms Pythium affects roots, in particular those of seedlings [...] General Pythium is considered a ‘weak pathogen’, meaning that it can usually only affect plants that are in a sub-optimal condition or suffer from stress [...] temperatures or sudden fluctuations in temperature. Pythium aphanidermatum mostly occurs at higher temperatures in the soil or irrigation water. Pythium

Phytophthora blight

higher water content than is optimal for crop growth. Phytophthora overwinters in roots, infected tubers and bulbs or in the soil in different stages: as oospores [...] infection is either by germinating sporangia or by zoospores produced in the sporangia. For germination on above-ground plant parts, leaf wetness is required [...] 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, since

Early blight

General The only known stage in all Alternaria species is the asexual stage. Conidia and mycelium overwinter in the soil and on crop residues and cause [...] are wet. Small differences in optimum temperature occur between species, but in general the risk of Alternaria infection is larger under quite warm and [...] sporulation within five days. Infection is both direct and through wounds and stomata. Spores are dispersed by wind and in some species through the splash of