Samantha Chigogo Herald Correspondent
Seed Co has successfully carried out trials of chemical options to prevent the destruction of maize and other cereal plants by a pest known as chilo worms (chilo partellus) that is spreading across the country.
In a statement yesterday, the Seed Co technical services team said it was fighting hard to curb the spread of the worms.
“Seed Co, in conjunction with chemical companies and some entomologists has carried out some trials of several chemical options to curb the pest in Shamva, Mazowe and Matebeleland through Bioassays and commercial field trials,” reads the statement.
“Some of the chemicals on the market that have worked to control the Chilo Worm in the trials include Karate Zeon, Blast super, Bulldock, Decis forte, Fortis k, Coragen, Vantex, Trigger and Ampligo.”
Seed Co said the mode of control was for both contact and systemic pesticides, applied by knapsack or boom sprayers or pivot during irrigation while systemic pesticides were applied at planting as seed dressing.
“A preventative spray of a systemic pyrethroid can be recommended at three leaf stage followed by contact pesticide sprays when the pest reaches Economic Threshold Levels (ETLs) or is noticed.”
Seed Co said further trials with other options were still being carried out throughout the country and farmers should also prioritise cultural ways of controlling effects of the worms.
“Crop rotations with non-grass crops e.g. legumes to break the life cycles of the pest is the smartest control measure, destruction of ratoon growths and other hosts for example sorghum, shamva grass and other grass weeds,” Seed Co said.
“Early weed (grasses) control, to destroy weeds, which act as alternative hosts and spraying decisions can be made when 3-10 percent of the plants are showing window-damage signs.”
The Seed Co technical team said outbreaks of the worm were beginning to be felt in larger parts of the country.
“Chilo worm in Zimbabwe has largely been subjected to the low lying areas of the country namely Muzarabani, Bubi and Chiredzi, which are normally hotter than the rest,” they said.
“There had been very little insignificant outbreaks in the middle and the high-veld until 2015/16 season when the temperatures soared and in 2016/17 there are reports of outbreaks throughout the country.”
Seed Co also warned farmers to be acquainted with the type of worm and dangers it posed to their harvest.
“The fully grown worm is the most destructive, at over an inch (2.5cm) long. They can be identified with their brown/yellow coloured body with stripes along the body spine.”
“They lay white fishscale-like on the leaf underside, making egg destruction difficult.”
The chilo worm attacks plants from three-leaf stage and the central leaves show typical bullet-shot holes and they leave behind dry horse manure-like droppings called frass, on the leaves particularly the central whorl.
Scouting must target those signs to try and distinguish them from maize stalk-borer signs where the leaves show a typical “window pane” damage on the leaf.
The damage includes holes on the stem causing significant stalk lodge, the cob and the tassel.
Government embarked on Command Agriculture targeted at funding the production of two million tonnes of maize on 400 000 hectares countrywide and there is need for Government and all stakeholders to fight the worms.