8 February 2024
Wireworms affect all crops – including maize.
Gerrit Nel, who farms with maize and groundnuts in Stella, North West, believes in regular soil analysis. He says the analyses conducted before the start of this season’s planting showed high wireworm pressure in certain areas.
“For the past three years, we haven’t applied any wireworm pesticide during planting in certain areas. As a result, the pressure has increased,” he says
The photo shows four maize plants. Three display strong and healthy roots, while one plant’s root development is weaker.
“The one with weaker roots didn’t receive wireworm pesticide while the others did,” says Nel.
Wireworm damage is not as visible in maize. Nel’s pesticide adviser, who spoke on condition of anonymity, says maize has a fibrous root system and generally forms many roots, making it difficult to see wireworm damage.
“You can more easily see it in other crops, such as soybeans and groundnuts. Farmers generally think they don’t need to worry as much about wireworm damage in maize, while in truth the plant suffers just as much damage as other crops.
What should you apply?
“There are both bad and good wireworms in the soil. It’s ideal to preserve the good ones because then they become stronger than the bad ones, which benefits crops,” says the pesticide adviser.
He says pesticide should be applied with the seeds during planting. Nel says it’s important for the pesticide to be placed alongside the seed and not on top because that inhibits seed germination. For the maize in the photo, 66 g of terbufos per 100 metre row was applied.
The pesticide adviser says any organophosphates, such as terbufos or orthophos, can be applied. “The disadvantage is that they also kill the good wireworms. The advantage is that they also kills other soil pests, such as false wireworms and black maize beetles.
“In South Africa, we have destructive wireworms and knot wireworms. The destructive wireworms cause greater damage, especially visible in soybeans and groundnuts.
“False wireworms are also a major problem in South Africa. They are transmitted by dung beetles. Above ground, the dung beetle poses no threat to the crops, but once the false wireworms enter the soil they cause significant damage.”
He says Velum (Reg. No. L9965, Act 36 of 1947) is also an ideal pesticide for wireworm treatment because it kills only the bad wireworms and none of the other soil pests.
Soil analysis and budgeting
The pesticide adviser encourages farmers who do not conduct annual soil analyses to do so.
Nel says he never misses a year. “For me, soil analysis is of paramount importance and I do it annually. Based on the results, advice from my pesticide adviser and my budget, I then make the final decision on what to apply.”
