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 [...] Inside the plant, the pathogens produce haustoria, small organs with which the pathogen can take up nutrients from the living plant cells. The pathogens [...] brown. On the underside of the leaf fluffy growth appears which is first white and later turns grey-brown. This is, in fact, the sporulation of the pathogens

Damping-off

bulbs. At first, the plants recover during the night, but later the plants wilt irreversibly. In potted plants the flower buds fall off. The side roots rot [...] of the root system survives. On the border between air and soil or substrate the plant turns brown. A typical symptom of a Pythium infection is the easy [...] enable the spores to move through water. The zoospores are chemically drawn to the growing roots of young plants and move towards them through the soil water

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 [...] dry leaves or leaves in the soil, but not independantly in the soil. Under humid conditions, bacteria ooze from the lesions on the leaves and form a secondary

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

Black sigatoka disease

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 [...] 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

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 [...] Damage symptoms The first symptoms of a cottony soft root ( Sclerotinia sclerotiorum ) infection are water-soaked lesions at the stem base. The plant above

Phytophthora blight

fungal growth on the leaves. The centre is grey-brown with a light-green edge. On the stem, elongated brown lesions occur, usually circling the stem. On potato [...] from the root to the foot, but direct infection of the foot also occurs. Exudates leaking from growing root tips promote germination and attract the zoospores [...] wind and rain causes the pathogen to be returned to the soil from infected plants. Dispersal in the soil happens via water, since the zoospores can readily

Bacterial wilt, brown rot

s roots on the stem. The vascular stem tissue is coloured brown and when the stem is cut, bacterial slime oozes from the wound. This is the way to distinguish [...] signs of wilting during the day which may disappear in the early stages of infection. Under conditions favourable for the bacteria, the whole plant will wilt [...] common with bacterial slime oozing from the cut. When the bacteria transfers to young plants through infected tubers, the wilting and collapse of plants happens

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 [...] stem seems wet and slimy. Above or below the hollow stem the vascular tissue keeps its normal colour. On the fruits, lesions first are small and sunken, w [...] 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

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 [...] brown discolouration of the xylem vessels which can be seen when the stems are cut. In banana, whole plantations may die and the soil may not be suitable