Moth Infestation Gobbling Way Through Tarakanki Crops
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Date:
Wed, 18 Dec 2002 07:35:09
-0500
From:
Stephen Tvedten <steve@getipm.com>
Organization: Get Set Inc. (www.getipm.com)
To: Paul Helliker <phelliker@cdpr.ca.gov>
Director, State of California, Department of Pesticide
Regulation
cc: Christine Whitman
whitman.christine@epa.gov
cc: clearance@inl.co.nz
Moth infestation gobbling way through Taranaki crops
TUESDAY , 17 DECEMBER 2002
By TERRY TACON
Dairy farmers' fodder crops in many parts of Taranaki are being devastated by
what is being called the region's worst infestation by diamond back moth
larvae in 30 years.
Some crops have been all but lost while hundreds of dollars have been added to the cost of others through spraying insecticides on them.
Commercial vegetable growers and home gardeners are also being affected, with extensive damage reported to cabbages and cauliflowers.
Veteran agricultural spraying contractor Jim Finer, Hawera, said he had never seen such extensive damage caused to brassica crops, turnips in particular, in his 30 years in the business.
The worst outbreaks have been in the Coastal region around Opunake, Rahotu and Pungarehu, but Mr Finer had been called to spray crops as far south as Patea, east to Mangamingi and north to Inglewood.
"The diamond back moth has always been around, but I have never seen anything like this.
"Some of the younger crops have been completely devastated.
"Those with more growth have a chance of getting through, but the ones hit when the plants are three inches high or less are pretty well ruined," he said.
Lower Ngariki Rd farmer Tim Hurley, who has been growing turnips for the past six years as a means of renovating pasture, said this year's paddock of turnips had been extensively damaged by the larvae.
Inspection of the young plants showed leaves eaten full of holes by the tiny green caterpillars.
Mr Hurley's crop has been sprayed, but there were still larvae and moths on many of the plants, indicating a follow-up spraying would be required.
"Turnips have been a good crop for me for breaking in paddocks for new pasture because I have simply been able to plant them and shut the gate while they grow. But not this year," Mr Hurley said.
Taranaki Farmers merchandise representative Gerard Svensden said Mr Hurley's situation was a common one among Coastal farmers growing turnips this season.
"Normally they put the crop in, check it once after about six weeks and then don't have to worry again.
"But this year the diamond back moth damage has meant a high degree of husbandry has been required," he said.
Mr Svensden said that many turnip crops had required an initial spraying with a synthetic pyrethroid and then a follow-up treatment with an organophosphate.
"The problem seems to be that the initial spraying kills about 95% of the larvae, but the remaining 5% and others laid by moths can still cause a lot more damage."
Russell Jordan, New Plymouth, who is chairman of the fresh vegetable sector of VegFed, said that commercial growers around the country were having a huge problem with diamond back moth larvae this year.
"I heard of growers in Ohakune who were spraying at night and the radiators of their tractors were clogged because there were so many moths about.
"Some growers have been spraying neighbouring paddocks of turnips as well as their cabbages and cauliflowers to make sure they get a control of the larvae."
Mr Jordan said many people found it difficult to believe that an insect as small as a diamond back moth could cause such problem to crops, but the larvae could do an enormous amount of damage.
Diamond back moths (plutella xylostella) are a common insect in Taranaki but do not normally cause any major problem.
Mr Finer said he suspected the colder spring Taranaki had experienced this year was responsible for the extensive damage to crops.
"The moths have incubated longer than usual and have emerged and produced larvae when crops have been more vulnerable than normal."
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