Tuesday, September 20, 2011

Nematodes...the Hidden Enemy?

Tropical Storm Lee blessed our area with several days of rain and cloudy weather for our Labor Day Weekend.  This storm along with ruining the holiday weekend festivities also coincided with our seasonal nematode flush that normally occurs during the fall.  The combination of poor weather and high nematode counts left us with some areas of stressed turf on our practice putting green.  Nematodes are microscopic worms that feed on plant roots much like a mosquito feeds on us.  They have a needle like feeding structure that pierces the plant root cell and then it sucks out the contents of the cell resulting in damage to the area.  When numbers are high enough the plant will be prone to other stresses including reduced water uptake, reduced plant vigor and an increase in drought and disease stress.  Nematode population levels naturally rise and fall and tend to peak in the months of April/May and August/September.

A product known as Nemacur (fenamiphos) was the staple and only real option of the golf course industry for the control of plant parasitic nematodes other than Curfew that must be slit injected into the surface.  Due to environmental concerns the EPA lowered this products use rates and eventually removed it from the market in 2007.  Since this time golf courses have been allowed to exhaust their remaining inventory as researchers scramble to find a replacement for Nemacur.  Since 2007 there have been a few bionematicides that have come to the market but none with the curative effectiveness of Nemacur.  These products merely help to reduce the amount of certain species of nematodes on a preventative program but are useless for curative treatments.

Along with our 2 permitted applications of Nemacur this year we have made 2 applications of a product known as Nortica ( bacillus firmus) to help manage high levels of root-knot nematodes.  This product may have helped to lower our root-knot nematode counts from earlier this May but it is not effective for ring nematodes.  Ring nematodes can be a problem at high levels and there are no other bionematicides currently available for control.

Our practice putting green has been the main battle ground this year with small areas of weak unresponsive turf while our putting surfaces out on the course have performed well. This fall we have increased our hand watering routine and our frequency of fungicide and fertilizer applications to help the turf survive the below ground feeding of the nematodes.  Hopefully scientists will be able to catch up and bring a new chemistry to the market in the very near future to help fill the void left by Nemacur's early departure.

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