PEST MANAGEMENT DECISION GUIDE: GREEN AND YELLOW LIST
Maize lethal necrosis disease
Maize lethal necrosis disease MLND is a combination of Maize chlorotic mottle virus and Sugarcane mosaic virus
- Eliminate host plants of thrips, aphids and plant hoppers that can transmit this disease. Clear and/or burn grasses around farm.
- Use clean seeds from a reliable source or certified seeds every season. Do not buy maize seeds from local markets. Do not recycle maize seeds from your field.
- Synchronize planting date among farmers of the area to break continuous disease spread between maize fields of farms.
- Plant before rain onset.
- Remove and burn maize stalks after harvesting if the disease is in your area.
- If your farmland is less than 500 meter away from infected farms, avoid growing maize.
- Rotate maize with non-cereal crops (e.g. beans, sunflowers) for three consecutive growing seasons.
- Get informed about the outbreaks of this disease in your area because it is new in Tanzania.
- Regularly visit the farm to identify the presence/absence of thrips, aphids and plant hoppers on the crop. Look under the leaves in the morning once per week from crop emergence onwards. These insect transmit the disease. If the disease is known to be in the area, and when 20 plants / quarter acre have these insects, consider controlling these insects.
- Observe symptoms of the diseases e.g. yellowing of top leaves, followed by drying up of leafs from edges inwards, and premature drying of husks and tassels. At late stage, maize plants will die in a scattered pattern across the field.
- If the disease is detected, immediate action is advised.
- Note the difference to grey angular leaf spot disease, which has in its early stage yellow stripes that are short (thin short angular) and not long along entire leaves as for MLND. Angular leaf spot rarely kills a plant.
- Note the difference to maize streak virus which has thinner yellow stripes along leaves than MLND. Unlike MLND, Maize streak virus usually does not lead to necrotic dead leaves and plants.
- Entirely uproot and burn/bury the diseased plants as soon as possible. Do not leave any diseased plant in the field as they will be a source of new infections.
- There exist no preventive or curative chemical sprays against MLND.
- Chemical sprays against the virus transmitting insects only make sense if all diseased plants have been removed.
- When using a pesticide, always wear protective clothing and follow the instructions on the product label.
- Farmers are not allowed to buy and use WHO toxicity class Ia, Ib, II products without special permits (Plant Protection Act Tanzania).
- Always consult recent list of registered pesticides (MAFC / TPRI).
Diafenthiuron products (Efenthiuron, Pegasus, and others)
WHO toxicity class III (slightly hazardous); diafenthiuron pesticide group; p.h.i. 7 d, r.e.i. 1 d, Max 3 sprays in min 10 d intervals, in mornings.
CREATED/UPDATED: September 2013
PRODUCED BY: Plantwise