Yellow spot virus
The yellow spot virus has been shown to be identical to the tomato spotted wilt virus. It infects over a 100 species of plants including peppers, tomato, tobacco, eggplant, potato, broad bean, spinach, chicory and peas. A number of wild plants, including some common weeds such as the black jack (Bidens pilosa), Emilia sonchifolia and Datura stramonium, are also host of this virus.
Thrips are vectors of this virus. When host plants of the virus are grown near to pineapple plants, the incidence of the yellow spot virus is considerably enhanced due to thrips migrating into the pineapple field. Wind carries thrips long distances and thus also plays an important role in the transmission of the virus. One of the symptoms in the fruit is a blackened, dry cavity in the side of the fruit due to one or more "eyes" having died. This is known as "dead eye". Infection of very young fruit results in an irregular arrangement of fruitlets as some fail to develop. Attacked fruits may also fail to develop a crown. Thrips feeding on the crown of fruits results in concentric ring patterns developing on crown leaves. These spots enlarge and the infection spreads into the fruit itself, by which time the crown will often have dried out. The flesh of fruits thus infected will be discoloured and necrotic below the butt of the crown. The whole fruit may eventually become affected.
- Control weeds in and around pineapple fields. This is very important for disease control because the presence of certain weeds leads to increased number of thrips.
- Field management offers potential effective control. Cut off the fruits showing early symptoms of infection. This will prevent the spread of infections into other fruits.
- Where this disease is a problem avoid planting near host plants of the thrips and the virus. Even if thrips are not strongly inclined to migrate from their favoured host plants, they will do so if disturbed, for instance by human passing, animals or machinery.
- Control thrips. For more information on thrips click here