• Downy mildew of rose

  For most downy mildews, the optimum temperature is around 15 °C. The closer the temperature is to these 15 °C , the shorter the leaf wetness period that [...] pathogens extruding from the stomata. In lettuce, the foot is infected first and this causes the plant to fall over. In cabbage the stem is also infected in [...] Inside the plant, the pathogens produce haustoria, small organs with which the pathogen can take up nutrients from the living plant cells. The pathogens

• Black sigatoka disease

  them, so the spores cannot be discharged from the lower leaves in the stack Use under-canopy (drip) irrigation to reduce splash dispersal Lower the humidity [...] or streaks on leaves of about one month old. The symptoms run parallel to the veins. Within a few days, the spots become a few centimetres in size and turn [...] conidia. The ascospores are wind-dispersed over longer distances, the conidia are splash-dispersed within the crop. Both types of spores cause the exact same

• Fusarium spp.

  upwards. At the same time, the plant produces gum as a defence mechanism to stop the fungus from spreading. This gum blocks the xylem and causes the wilting [...] This species is the only Fusarium that actually grows inside the vascular system of the host plant and spreads upwards inside the plants. The other species [...] towards the foot of the plant and enters the vascular system. Inside the vessels, the fungus produces mycelium and many spores (microconidia), which are

• Angular leaf spot

  lesions on the underside of the leaf. They enlarge to angular spots, often limited by the small veins. The distinctive feature is the way the lesions look [...] 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 [...] conditions are humid, a viscous bacterial exudate forms on the underside of the leaf. This exudate changes to a white film when it dries. Lesions may merge as they

• Botrytis

  cinerea ) is part of the foot rot complex, which causes rotting of the foot and may cause death of the plants. In cucumber and tomato the fungus causes lesions [...] lesions on pruning wounds. These lesions may encircle the stem, so the part of the plant above the lesion wilts and dies. In vegetables and strawberry, grey [...] that it excretes compounds that kill the plant cells and then uses the content of the plant cells as nutrients. On the infected area, new spores are formed

• Bacterial soft rot, bacterial stem rot

  wilt at the time of first harvest or after that. The pith disintegrates and the stem becomes hollow. Because of the bacterial growth in the pith, the stem [...] 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 [...] plants or in the soil in low densities. It has also been found in the gut of insects, possibly spreading from decaying vegetation to the growing crop that

• Cottony soft rot

  base and the roots, whereas the ascospores infect the above-ground plant parts. In greenhouses, usually only mycelium is produced by the germinating sclerotia [...] sclerotia. The fungus grows quite rapidly inside the plant and kills the host cells. On the infected plant tissue white, fluffy mycelium occurs with new [...] new dark sclerotia. The fungus also infects seeds and tubers, thereby creating a source of infection for the next crop. The dispersal to neighbouring plants

• Fusarium wilt

  oxysporum is the only Fusarium that actually grows inside the vessel system of the host plant and spreads upwards inside the plants. The other species [...] Fusarium oxysporum is the species causing vascular wilt. First the leaves turn yellow and wilt, mostly on one side of the plant. Finally, the whole plant wilts [...] place as infection of the roots at the root tip or in small wounds, for example where lateral roots branch off from the tap root. How to prevent Fusarium wilt

• Pea blight, leaf and pod spot

  transmitted on the outside of the seed coat and cause primary infection. The conidia germinate and infect through the stomata or directly through the cuticle [...] and surrounded by a 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- [...] on leaves, stems and pods of peas. The spots on leaves and pods are round, on the stems they are more elongated. The lesions are light brown, sunken and

• Early blight

  occur at the side of the stem. Life cycle and appearance of Early blight From the primary infection of leaves, Alternaria solani can spread to the flowers [...] spores surviving in the soil are the main source of infection. Especially wheat and barley reduce the number of surviving conidia in the soil. Use resistant [...] 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