Crazy roots, hairy roots, crown gall

galls on the stems, which are first white and later turn brown. Only Rhizobium radiobacter causes galls and tumours on underground plant parts and on the [...] 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 [...] hygiene protocol, including disinfection of tools, drippers, gutters etc. Adjust the work order in greenhouses to fit with the hygiene protocol Disinfect

Powdery mildew

stomata on the underside of the leaf. On the upper side, yellow spots are noticeable. In case of a severe epidemic, the fluffy colonies also appear on the [...] fungus causing powdery mildew is extremely sensitive to water and ‘hides’ on the underside of the leaves. Therefore, this is where the colonies mostly occur [...] layer of plant cells. Most of the fungus remains on the outside of the plant surface. On the mycelium on the plant surface, new conidiophores are formed

Pea blight, leaf and pod spot

symptoms Ascochyta pisi causes spots on leaves, stems and pods of peas. The spots on leaves and pods are round, on the stems they are more elongated. The [...] 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 [...] General Ascochyta pisi is a fungal plant pathogen that causes A scochyta blight on pea (leaf blight or pea blight) and lesions of stems, leaves, and pods

Fusarium spp.

mycelium cells) or mycelium. Survival is also possible on seed, greenhouse structures, tools and machinery. Primary infection is either seed-borne or takes place [...] Fusarium spp. is a group of soil-borne fungi with many different species. Fusarium is widespread and can infect a range of host crops. Many species are [...] oxysporum ( Fusarium wilt ) is the species that causes vascular wilt. Initially, the leaves turn yellow and wilt, mostly on one side of the plant. Finally

Bacterial spot

spots may merge with lesions on the petioles and stems and form long dark streaks. On fruits, first small black specks are seen on green fruits. The specks [...] survives on volunteer tomato plants in the field and on diseased plant debris. The bacteria are also seed-transmitted. Disease development is favoured [...] General Xanthomonas vesicatoria is a bacterium that causes bacterial leaf spot on peppers and tomatoes. Damage symptoms Xanthomonas vesicatoria in tomato

Bacterial canker of tomato

years. On other fields on the same farm, no seed potatoes can be grown for one year after infection. Damage symptoms Clavibacter causes spots on stems, [...] the affected field and potatoes from other fields on the farm, are labelled as ‘suspect’ that year. On the infected field no potatoes or other Solaneceaous [...] They turn brown but don’t fall off. On stems and shoots light stripes form, which then tear, allowing cankers to form. On tomato leaves, water-soaked lesions

Fusarium wilt

the soil and on crop residues of infected plants as chlamydospores (thick walled mycelium cells) or mycelium. Survival is also possible on seed, greenhouse [...] 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 [...] post-harvest decay. Fusarium oxysporum is the species causing vascular wilt. First the leaves turn yellow and wilt, mostly on one side of the plant. Finally,

Gummy stem blight

foot and higher up on the stem. On the lesions, golden-brown gummy drops occur, hence the name gummy stem blight. On the lesions, black specks, the new fruiting [...] simultaneously. The spores germinate when free water is present on the plant, at high relative humidity (RH) and on wounds. Leaves can be infected directly, through [...] bryoniae) is a fungal plant pathogen that causes gummy stem blight. Damage symptoms Mycosphaerella cucumis in cucumber causes brown lesions on the foot

Downy mildew of Cucurbits

germination free water is required. For most downy mildews, the optimum temperature is around 15 o C and the closer the temperature is to this, the shorter [...] General Pseudoperonospora cubensis is a plant pathogen causing downy mildew on cucurbit crops like cucumber, cantaloupe, pumpkin, watermelon and squash [...] fruits. They cause lesions on the upper leaf surface, bordered by the veins, which are first yellow and then turn brown. On the underside of the leave

Grape downy mildew

e, characteristic ‘oil spots’ on the upper surface of young, actively growing leaves, followed by downy white growth on the underside, are typical early [...] symptoms usually appear 7–10 days post-infection (depending on temperature and humidity), the disease is often well-established before it can be visually detected [...] to light-green oil spots on the upper leaf surface, often angular and limited by leaf veins White to greyish downy growth on the underside of leaves under