The white fly and aphid causes the sweet potato virus disease. They transmit the disease called the sweet potato virus.
Sweet potatoes are mainly affected by the sweet potato virus disease and Altenaria blight.
Sweet potato Alternaria is a fungal disease, transmitted through spores that can easily be moved by wind, and rain splashes.
The virus is capable of causing 100% yield loss while Altenaria can cause yield loss of about 2.5 to six tonnes per hectare.
What brings the pests?
The pests attack gardens based on the environment conditions. For example, higher temperatures favour the breeding of pests.
That is why the weevil is mainly found in North-eastern Uganda and West Nile due to higher temperatures compared to the western region, which is relatively cooler.
The weevil spreads through proximity. If a farmer’s crops are infected, chances are high that it can move to the neighbouring farm.
How pests attack the potatoes
The weevil attacks sweet potatoes at an early stage. First, they feed on the leaves (forage), lay eggs on them, which hatch into larvae. The larvae then eats up the leaves stunting growth.
The weevils also make tunnels and use cracks that occur due to higher temperatures to enter the roots which they feed on, hence causing 100% yield loss.
The roots or vines damaged by the weevil cannot be fed to domestic animals. The weevils produce a toxin that is harmful to the health of animals.
Since there are no resistant varieties, but traditional methods, like early harvesting, weeding to cover the cracks that the weevils use to enter into the soil to eat the roots.
Other methods are timely planting to evade the onset of higher temperatures which favour weevil development and inspecting the vines before planting will help control the pest.
When the vines are infected with the virus, the plants become yellow. The yellow leaves curl and have a mosaic appearance (dark green mixed with light green and yellow).
With time, the plant becomes stunted and in severe cases, the plants fall off.
In addition, plants develop black lesions, on the stem, leaves, and vine. As they enlarge, leaves become yellow and fall off.
At the moment, there is no control for these diseases, but farmers are still using the traditional methods to control.