Citrus mealybug

male nymph forms a dark brown ‘prepupa’ from which a pupa rapidly develops, inside a white cottony cocoon. Females undergo little changes in form, passing [...] therefore ingest large quantities of sap, getting rid of the excess sugars in the form of honeydew. Characteristically, dark sooty moulds ( Cladosporium spp .) [...] 2.5 - 4 mm long and 2 - 3 mm in breadth. Seen dorsally, they have an oval form; they are soft and covered with a fine waxy material. They move very little

Angular leaf spot

are translucent. When conditions are humid, a viscous bacterial exudate forms on the underside of the leaf. This exudate changes to a white film when it [...] Under humid conditions, bacteria ooze from the lesions on the leaves and form a secondary source of infection. They are dispersed by rain, irrigation water

Blight of pepper

mycelium cells which are resistant to desiccation) or mycelium. Zoospores are formed from the overwintering structures which infect the host. Zoospores are spores [...] (structures containing sporangia, a type of spores) with sporangia are formed that protrude through the stomata. Secondary infection is either by germinating

Black root rot of cucurbits

disinfection needs to be applied thoroughly and evenly. Phomopsis sclerotioides forms sclerotia which can survive adverse conditions for years in the soil, but [...] line on cucumber roots. The lesions are slightly sunken and are mostly formed around the point of attachment of lateral roots and root hairs. The lesions

Apple collar rot

mycelium cells which are resistant to desiccation) or mycelium. Zoospores are formed from the overwintering structures, which infect the host. Zoospores are [...] (structures containing sporangia, a type of spores) with sporangia are formed, that protrude through the stomata. Secondary infection is either by germinating

Verticillium wilt

brown stripes occur on the stem. In tomato, sometimes V-shaped lesions are formed on the leaf, between the veins. 'Early dying' disease of potato only occurs [...] In the senescent tissue, the resting mycelium or the microsclerotia are formed. The spread of the fungus by mycelium growth is limited. Dispersal from

Diamond back moth

pairs of prolegs; one pair of prolegs protrudes from the posterior end, forming a distinctive 'V' shape. Throughout their development, larvae remain quite [...] (Plutella xylostella) are covered with a white, loose, silken cocoon, usually formed on the lower or outer leaves. They often stick to leaves and frequently [...] cream or light brown band along the back, which is sometimes constricted to form one or more light-coloured diamonds, thus the common name diamond back moth

Phytophthora blight

mycelium cells which are resistant to desiccation) or mycelium. Zoospores are formed from the overwintering structures which infect the host. Zoospores are spores [...] (structures containing sporangia, a type of spores) with sporangia are formed that protrude through the stomata. Secondary infection is either by germinating

Bacterial canker of tomato

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 occur, usually

Glasshouse potato aphid

immediate effects of piercing by the aphids are visible in lower leaves in the form of yellow patches. Heavy yellowing may even be followed by defoliation. Life [...] potato aphid Aphids have a complex life cycle, with both winged and wingless forms of adults and a great variety in colour. When reproduction is asexual, the