Downy mildew is a serious problem in greenhouses especially under cold humid conditions. It is caused by the casual organism Bremia lactucae. Of the commercial crops, lettuce is most affected, but is also prominent with Endive, Escarole, Chicory, Salsify and Globe Artichoke. The fungus grows very fast and when the symptoms appear on the leaves, [...]
[/su_collumn] Sclerotinia infects crops such as lettuce, escarole and endives. Tomato fruit are seldom affected. It manifests itself as a damping-off when planted, wilting symptoms also referred to as “drop”. When fruit or leafy crops are transferred and infected by Sclerotinia, it is called as “watery soft rot”. The disease is serious during [...]
Grey mould is found on lettuce, escarole, endive and globe artichoke. The disease is most important during transit of these crops. The disease is caused by Botrytis cinerea Fr. Grey mould contributes to damping-off, especially in lettuce seedlings. Grey mould symptoms The symptoms are typical of those of damping-off. The fungus is usually identified by [...]
Description of whiteflies Whiteflies are about 1.5mm long, the adult is white which resembles a tiny moth. They produce oblong eggs, pale green to purple and are inserted into the lower leaf surface, often in a circle or a crescent. Each egg is about 0.2 mm long. The tiny, first instar nymphs are yellow with [...]
Septoria leaf spot is one of the most destructive diseases on tomato and is caused by Septoria lycopersici. It is most destructive during moderate temperatures and high rainfall. The disease destroys so much of the leaves that the plants fail to mature their fruits properly. Symptoms of Septoria leaf spot The disease occurs at any stage [...]
Cutworm description Black cutworm moths have dark brown forewings, light-coloured hind wings, and a wing expanse of 38 to 51 mm. Granulate cutworm moths have yellowish-brown forewings and a wingspan of 38 to 45 mm. Variegated cutworm moths may be yellowish or brownish with a wingspan of 38 to 50 mm. Cutworm eggs are white [...]
Anthracnose is caused by the fungus Colletotrichum phomoides and is a common and widely distributed rot of ripe tomatoes. The disease can cause serious losses after the product is harvested. In lettuce it is caused by Marssonina panattoniana (Berl.) Magn. Symptoms of Anthracnose Infected fruits show a small, slightly sunken water soaked circular spot which become [...]
Bacterial spot is caused by Xanthomonas vesicatoria and is most noticeable in its effect on fruit. However it may also cause considerable injury to the foliage of seedlings and plants in the field. Bacterial spot occurs during rainy periods. Symptoms of bacterial spot Leaflets show small irregular dark spots of greasy appearance and the centres [...]
Fusarium wilt (Fusarium oxysporum) is one of the most damaging fungi that infects tomatoes. Fusarium wilt is a soil borne disease and infects both soil grown tomatoes and greenhouse tomatoes. During high temperatures the disease can cause significant crop damage but during low temperatures there is generally little damage. There are currently two races that [...]
