Research on using non-chemical methods to control potato pests is delivering groundbreaking results.
A newly published paper from the Biology Husbandry Unit (BHU) Future Farming Centre and Lincoln University, detailing the results of field trials, shows the use of a mesh cover over the plants was very effective in controlling tomato potato psyllid, or TPP, as well as reducing potato blight.
One of the authors of ‘A field evaluation of the effectiveness of mesh crop covers for the protection of potatoes from tomato potato psyllid’, Dr Charles Merfield, says TPP can potentially cause severe crop loss due to phytotoxic saliva and transmission of the bacteria Candidatus Liberibacter Solanacearum.
The bacterium is believed to cause diseases such as ‘psyllid yellows’ in tomatoes and potatoes, and ‘zebra chip’ symptoms in potato tubers.
"The potential in the developed world to use mesh which is very safe, in place of chemicals, is very exciting," Dr Merfield says.
The arrival of TPP in New Zealand led to potato, tomato and pepper growers increasing their frequency of insecticide use, which disrupted integrated pest management programmes that were already in place, he says.
Over two growing seasons in Canterbury, potatoes growing under mesh covers were found to have much reduced numbers of TPP nymphs and adults, increased tuber size, increased overall yield and enhanced storage potential compared to uncovered plots.
There had been no effective TPP controls for purely organic growers.
The mesh can also control a wide range of pests on many different field crops, for example, it is already being used by organic growers to control root fly on carrots, Dr Merfield says.
The mesh crop covers are made of monofilament plastics, such as polyethylene and polypropylene, woven in a plain weave. They form a barrier between insect and crop.
Dr Merfield says the mesh covers appear to be an ideal way of controlling TPP on potatoes and are preventative rather than curative like agrichemicals. However, there will be more work to validate the results for which funding is already in place.
Lincoln University Agricultural Sciences senior lecturer Dr Simon Hodge, another author of the paper, says mesh crop covers have been widely used in Europe for nearly two decades for control of a large number of pests, both insects and vertebrates on a wide range of crops.