Grain diseases to look out for

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AS farmers take to the fields following rains received over the past week, they are eyeing a bumper harvest.
The last season did not bring much joy as yields were negatively affected by drought.
Farmers were not only affected by the El Nino that hit the southern African region, but inadequate funds were a major hindrance to maximum production, with smallholder farmers being the most affected as they do not have the requirements to access loans.
Lack of cheaper finance to procure inputs, the prevailing liquidity constraints and ever-changing rainfall patterns are drawing back crop production.
Farmers have, however, not lost hope.
They remain upbeat.
Planting has already begun.
Given the time, effort, hard work and determination shown by farmers, huge rewards are expected.
As farmers intensify planting, calls have been made for them to be on the look-out for pests and diseases.
Pests and diseases, if not controlled or prevented, can negatively affect yields.
Agronomist Ivan Craig said local grain is normally affected by stalk borer.
Stalk borer, a pest that feeds mainly on maize and sorghum, feeds on plant stalks and upper leaves, reducing flow of water and nutrients throughout the plant.
Plants then wilt, and either die or have stunted growth.
“The stalk borer multiplies quickly, especially in hot conditions and most farmers have been negatively affected in past seasons,” said Craig.
“If the issue of controlling stalk borer is not taken seriously soon, it will be a national disaster.
“Last year there was an outbreak in Matabeleland.”
Statistics indicate more than 10 percent of the country’s grain output is lost annually and this translates to US$60 million worth of maize output.
Craig urged farmers to take precautionary measures to protect crops.
“Farmers should apply chemicals that destroy stalk borer after four weeks of planting and this should be done even when no signs of the pests are found,” he said.
“The application is best done manually with farmers sprinkling pesticides at the tip of the plant.”
Farmers can be sure of the presence of stalk borer if young plants have holes and windows in leaves while small dark caterpillars can be seen at the base of leaves.
The caterpillar is pinkish with more or less distinct black spots along its body with a fully grown one measuring up to four centimetres long.
In severe attacks, the central leaves die.
In older plants, the young caterpillars bore into the main stem and later move up into maize cobs.
According to an article produced by HDRA, an organic research organisation, stalk borer lays its eggs on the underside of leaves in columns stretching from the stem.
“The eggs are white, but get darker with age,” read the article.
“They hatch into a larvae after about 10 days and develop from being small and black to pink caterpillar with black spots on its back.
“Young caterpillars crawl to the base of a leaf and eat plant tissue.
“After sometime they bore into the stem and feed there until they are fully grown.”
Farmers can put in place measures to monitor, control and prevent stalk borer.
Farmers can use light traps which help provide useful information about the population of moths and therefore of caterpillars.
Craig said general management of fields aided pest movement control.
“Fields should be kept clean, without any weeds, including surrounding areas as this helps control pests,” he said.
“After severe outbreaks, stubble should be ploughed into the soil or burnt to kill any remaining larvae.”
Crop rotation aids stalk borer control as it separates pest space and time from its host plant.
Through crop rotation, pest-life cycles are interrupted by depriving them of their food source.
Experts contend farmers should rotate crops which have few common ‘enemies.’
Growing maize-cowpea mixtures reduces incidences of stalk borer.
One traditional method farmers can use is sprinkling cow urine on crops.
According to HRDA, farmers can collect cow urine, let it stand for two weeks in sunlight before mixing it with water using the ratio one part urine to two parts water.
Care should, however, be taken when using this method so as not to burn tender leaves with too high a concentration.
The timing of any kind of spray is crucial as crops should be sprayed before moths lay eggs or spray caterpillars when they are at their most vulnerable that is feeding at the base of leaves.
Farmers are therefore encouraged to take heed.

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