Robert Woolley Dave Wilson Nursery Hickman, CA growers of deciduous fruit, nut & shade trees for commercial growers & the home garden

 primarily field-grown, trees sold bareroot  some stock grown in containers  1 to 2 years in ground  zero tolerance for nematodes Dave Wilson Nursery

 trees sold to commercial growers must be produced under CA Dept of Food & Agriculture (CDFA) Nematode Certification Program  CDFA’s Nematode Certification Program requires soil treatment or nematode sampling  soil treatment must eliminate nematodes to 4 to 5 feet deep, for 1 to 2 years Dave Wilson Nursery

3 soil treatments used in CA for control of nematodes in field grown deciduous trees:  methyl bromide with chloropicrin  Telone II (1,3-dicholoropropene)  Vapam (metam sodium)

methyl bromide  only soil treatment effective in “heavy” soils  only nematicide in general use that also effectively controls weeds  granted limited use in CA nurseries by Montreal Protocol, under QPS exemption  rates of chloropicrin from odorant to as high as 33% (strawberries up to 50% “pic”)  a “biocide”, so it disrupts soil ecology

Telone II  approx 95% of CA tree nursery Telone II treatments are done under tarp--tarping may provide some weed control  use limited by “township caps”  30 days (minimum) to plant back  putatively more benign to soil ecology than methyl bromide

Vapam  requires water as carrier to target pest, but sprinkler application limited as it’s highly volatile  drip application impractical in nurseries  very limited use with Telone II due to cumbersome application rig

non-chemical alternatives crop rotation and/or extended fallow -maybe OK--limited by time required mechanical (super-heated water/steam) -questionable efficacy & cost? Star Wars devices -cost? & soil ecology concerns

methyl iodide -little to no interest due to phytotoxicity propargyl bromide -tends to explode Nemacur, Vydate & Furidan (sp?) -registered for use in CA via drip but not used due to impracticality brassicas & other veges -insufficient nematode kill -impractical other “alternatives”

next steps?  plant breeding for immunity -very long term but important to pursue  novel approaches to killing nematodes and controlling weeds & disease -new chemicals? -genomics?  Grow trees solely in containers -the ultimate solution?