Stem/stalk borers are the most important insect pests of maize in Kenya. Yield losses in areas vary between 10-70%. Young plants have pinholes in straight lines across the newest leaves. This is the time to treat - before the larvae move on into the stem.
Control & treatment
- Early Planting
- Field sanitation
- Crop rotation
- Use Push-pull technology
- Desmodium (Desmodium uncinatum) when planted in between maize rows keep the stem borer moths away. This plant produces chemicals that repel stem borer moths. Napier grass (Pennisetum purpureum) and Sudan grass (Sorghum vulgare sudanese) are good trap crops for stem borers. Napier grass has its own defense mechanism against crop borers by producing a gum-like-substance inside its stem, this prevents larva from feeding and causing damage to the plant. Both grasses attract stem borer predators such as ants, earwigs, and spiders. Sudan grass also increases the efficiency of natural enemies, in particular parasitic wasps, when planted as border crops.
- Apply Thiodan 3.5 G or Ambush 0.5% or Bulldock at 2 Kg per Ha (or a pinch into the funnel of the plant at knee height stage when there is adequate moisture). You can spray the plant with Dimethoate etc
Cutworms (Agrotis spp. and other species)
Cutworms cut maize seedlings at or a little below ground level, make small holes along the initial leaves, or remove sections from the leaf margins.
- Spray Bestox 10 EC when soils are moist. You can also apply FASTAC
Maize aphid (Rhopalosiphum maidis)
It is a soft dark green to bluish-green in colour insect. The insect feeds on the inflorescene and young leaves especially during dry periods. This causes yellow mottling of leaves
- Spray with Dimethoate , Malathion, Karate
(Microtermes spp., Macrotermes spp., Allodontermes spp., and Odontotermes spp)
- Often referred to as “white ants”, they occasionally cause partial or total defoliation of maize seedlings, but are mainly damaging to older maize plants. Severely damaged plants may lodge and be completely destroyed by termites. The longer a field has been cultivated, the greater will be the yield losses caused by termites. Their feeding inside the stems causes the plant to wither and sometimes die. Termites begin to attack the roots and stems about three months after planting, and eventually cover with tunnels built of soil. As plants mature the amount of damage increases rapidly. Infestation is particularly serious in dry season.
- Destroy termite nests, remove and kill the queen Apply termite killers like Termindol, Imaxi Seed dressing with Marshall 35 SD
- The attack starts in the field where the female lays eggs in a slight hollow on the maize seed. The hatched larva bores thin tunnels beneath the seed coat leaving circular holes on the surface of the grain.
- Early harvesting
- Clean and dust with Actellic Super or Sumicombi the store well before use
- Dust the shelled maize with either of the following chemicals Actellic Super, Sumicombi, Skana Super grain dust, Spintor Dust, Super Malper dust at a rate of 50 g per 90Kg bag
The larger grain borer
- (Prostephanus truncatus) It attack stored maize grains. Both the adults and the larvae (grubs) of the beetle feed in the grains. Adults come from infested cobs in the field or from an infested maize store and lay eggs in the grains. Attacked maize grains lose all their contents and are not fit to eat. These pests become a serious problem in short time if no control measures are applied. The larger grain borer also attacks wooden structures of the stores.
- Leave the maize to dry completely in the field before stooking.
- Use the following chemicals.
- Dusts - Actellic Super, Sumicombi, Skana Super grain dust, Spintor Dust, Super Malper dust at a rate of 50 g per 90Kg bag.
- Spray Actellic Super 50EC in the grain stores
- Fumigants ( Restricted to NCPB and other large grain handlers)- Tablets like Celphose, Quickphos, Gastoxin tablets, Detia gas Ex-Tablets, Ex-B Fumigation Bags, Dages plates
Red Flour Beetle Tribolium spp
- It is a small reddish brown beetle that infest flour and previously damaged and broken grains
As for maize weevil