Nematicide guidelines stress calibration importance

New guidelines for the application of Nemathorin for soil pest control make the correct calibration of application equipment essential, advises Graham Basil of calibration consultant Apcal.

With latest guidance showing that overall application and incorporation of nematicides gives the most reliable results, potato growers must ensure that all equipment is maintained, calibrated and operated correctly, he says.

Mr Basil points out that the most common mistakes include the wrong assembly of loose metering parts, failure to check the number of land-wheel turns per 100m and not doing a daily reconciliation of how much nematicide is being used.

“The daily reconciling is so important,” he stresses. “It’s too late to find out that you’ve used the wrong amount on the whole treated area – you must check per day or per small block.”

Measuring machine output is done by measuring the amount of nematicide applied per 100m. “Start by measuring the machine working width, then find the number of spiked land wheel turns per 100m. Preferably, do this in the field.”

The output is then determined by turning the hopper shaft the equivalent of 100m, to produce the one-to-one output. “Each outlet should be sampled separately. The aim is to have the individual results within 10% of the average.”

This involves catching the granules from all outlets for the equivalent of 100m and then weighing the output using scales. “So you need to have enough containers to catch the granules for all the outlets at the same time.”

Calculating the hopper output is more complex, he notes. “You need to take your figure for grams per 100m and multiply it by the working width. That gives you the amount in kg/ha.”

The drive ratio can then be calculated to give the ratio for any given sprocket/pulley combination, adds Mr Basil.

“Once you’ve got the required ratio, you should then consult the Syngenta chart and select the nearest ratio below the one you have, depending on whether it’s a chain drive or belt drive machine. This corrects for any errors.”

Nemathorin has two approved rates in the UK – 30kg/ha for control of PCN and reduction of spraing and 15kg/ha for reduction of wireworm damage.

“For Nemathorin only, you get less than 100g of product per 100m. But if you’re using Vydate or Mocap, which have lower densities and weights, the rate of use will be higher,” says Mr Basil.

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