Damping-off

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 [...] aphanidermatum mostly occurs in young plants and damage is more extensive in young crops. Damage symptoms Pythium affects roots, in particular those of seedlings [...] substrate the plant turns brown. A typical symptom of a Pythium infection is the easy stripping of the skin from the root cortex with a finger nail. Life cycle

Charcoal rot

General Macrophomina phaseolina is a common soil fungus in warmer regions, causing charcoal rot. It has a very wide range of host crops, many of which [...] crops in temperate regions it is therefore not a problem. How to prevent Charcoal rot Plant in fields with no history of the disease Use disease-free planting [...] but this is not considered a main source of infection. Optimum conditions for this fungus are temperatures above 32 °C and dry conditions. In field crops

Crazy roots, hairy roots, crown gall

yet been defined. The assumption is that the bacteria survive in the soil, but it is possible that first infection is from the propagation material. Infection [...] be caused by a change in the hormonal system of the plant resulting from the Rhizobium infection. Rhizobium rhizogenes puts a Ri-plasmid in the plant tissue [...] Furthermore, infection is characterized by excessive root growth (crazy roots). In greenhouse vegetables, the roots overgrow the substrate and in severe epidemics

Black rot of carrots

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 [...] Species may differ in specific symptoms. Life cycle and appearance of Black rot of carrots Black rot of carrots ( Alternaria radicina ) is a seed-transferred [...] and at a relative humidity (RH) of over 90% or when the leaves are wet. Small differences in optimum temperatures occur between species, but in general

Black leg 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 [...] substrate the plant turns brown. A typical symptom of a Pythium infection is the easy stripping of the skin from the root cortex with a finger nail. Life cycle [...] Pythium affects roots, in particular those of seedlings. Infected plants lag in growth. Seedlings fall over (‘ damping-off ’). In slightly older plants

Apple collar rot

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 [...] General Phytophthora cactorum is a plant pathogen that causes root rot, rhizome rot of strawberry, apple rot, apple collar rot and crown rot. It has an [...] s containing sporangia, a type of spores) with sporangia are formed, that protrude through the stomata. Secondary infection is either by germinating sporangia

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 [...] or by zoospores produced in the sporangia. For germination on above-ground plant parts, leaf wetness is required. Dispersal is by wind and rain causes the [...] borders and white fluffy fungal growth on the leaves. The centre is grey-brown with a light-green edge. On the stem, elongated brown lesions occur, usually

Cottony soft rot

as cottony soft root, is a plant pathogenic fungus. It has a very wide range of host plants. Damage symptoms The first symptoms of a cottony soft root ( [...] Sclerotinia sclerotiorum ) overwinters as sclerotia and mycelium in dead and living plant material in or on the ground. Sclerotia germinate at temperatures between [...] whereas the ascospores infect the above-ground plant parts. In greenhouses, usually only mycelium is produced by the germinating sclerotia. The fungus grows

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 [...] and at a relative humidity (RH) of over 90% or when the leaves are wet. Small differences in optimum temperature occur between species, but in general [...] st storage at 0-1 o C. A. brassicae and A. brassicicola : adjust the sowing date to avoid conditions conducive to infection. In greenhouses: avoid high

Bacterial spot

Xanthomonas vesicatoria is a bacterium that causes bacterial leaf spot on peppers and tomatoes. Damage symptoms Xanthomonas vesicatoria in tomato causes small [...] due to rain, fog or overhead irrigation. Infection is through stomata and wounds. The dispersal is in windblown water drops, mechanical means such as clipping [...] into brown spots that look like scab. These spots may be surrounded by a halo. In pepper, the spots on the leaves are also round and small to start with