Managing Nematodes and Tomato Ring Spot Virus in Vineyards John M. Halbrendt Penn State University, Fruit Research & Extension Center, Billerville, PA
Tomato Ringspot Virus on Chardonnay Hen and chick symptom of ToRSV infection
Broadleaf Weeds natural reservoir of ToRSV - at least 23 common weeds are alternate hosts. Also - ToRSV carried in weed seed and can be graft transmitted 3
The Tomato Ring Spot Virus is vectored by the Dagger nematode (Xiphinema americanum) The Dagger nematode: Very common in the mid-atlantic region Has a broad host range Long lived nematode (up to 3 years) Weak parasite Efficient vector of ToRSV
Virus Transmission The virus is transmitted from infected weeds to vines by dagger nematodes 5
Virus Control = Prevention START WITH A CLEAN SITE Remove virus reservoirs. Test for nematodes Consider previous crops Check out the neighborhood
Only Plant Clean Vines Buy certified virus-free vines. Buy from a reputable nursery Ask questions! Are the vines virus-tested? Tested for which viruses?
DON T INTRODUCE PROBLEMS Distribution of ToRSV through propagation
What to do if you find virus infected vines in the vineyard Remove symptomatic vines as soon as they appear. Prevent re-growth. Kill/remove as much root as possible (herbicide/fumigation). Carefully monitor nearby vines over next 2-4 seasons.
Repeated herbicide use results in: Loss of organic matter Increased compaction Increased susceptibility to erosion Clean cultivation with herbicides is a common practice to help prevent virus introduction.
Good nematode management in vineyards requires preventive measures. Once a nematode problem develops it is difficult to correct. 12
Chemical control for nematodes Treatment Rates
Fumigant application has gotten safer Nitrogen tank supplies pressure for transfer of fumigant 14
Personal Protective Equipment Respirator Coveralls Chem. Resistant Apron Gloves 15
Dry disconnects make transfer safer 16
Soil fumigation is a very effective for suppressing plant-parasitic nematodes
Broadcast Application Need to seal chisel trace to minimize fumigant loss Gas moves in all dirrections from point of fumigant injection 18
How effective is Fumigation? Dagger nematode control S = spring F = fall 19
Soil Fumigants New regulations 2010 Additional measures added 2011. Regulations include new requirements for buffer zones and added safety measures applicators must comply with current regulations and requirements. Soil Fumigant Toolbox website: Provides easy access to current requirements www.epa.gov/pesticides/reregistration/soil_fumi gants. 20
Vydate L Oxamyl - 42% Insecticide/Nematicide DuPont [Methyl N N -dimethyl-n-[(methyl carbamoy)oxy) -1-thiooxamimidate] Contact nematicides such as Vydate must be incorporated into the soil either mechanically or with water to be efective. 21
Increasing interest in the development of alternative nematode controls Loss of effective chemicals Human safety Environmental health Cost Organic market / sustainable agriculture 22
PSU Field trials - rotation crops / green manures for nematode control 23
Biofumigation The control of soil-borne diseases by release of isothiocyanates from plant tissues. 24
Biofumigation Chopped and Tilled Rapeseed (Green Manure) glucosinolates toxic isothiocyanates
Rapeseed Green Manure Factors Affecting Efficacy Rapeseed cultivar Weeds Plant condition Soil moisture Plant size (Biomass) Soil temperature Effective incorporation 26
Population of P. penetrans after Incorporation Halbrendt, J.M. PSU,FREC. Treatments
Rapeseed can provide other benefits A thick stand of rapeseed can suppress weeds Rapeseed makes a good winter ground cover 28
The rapeseed taproot can penetrate deep and loosen compacted soil Soil Horizons A B C Photo by Dr. R. Weil
Sampling for Nematodes "T" type sampling tools ideal for collecting most soil samples. When sampling collect cores in a zig-zag pattern across the orchard Combine 20 subsamples to make one sample for testing. A soil sample should not represent more than 3-4 acres *Keep samples cool/from heat and sunlight
University of Delaware Plant Diagnostic Clinic 151 Townsend Hall Newark, DE 19716-2170 Phone: 302-831-1390 Fax: 302-831-0605 E-mail: bobmul@udel.edu Website: ag.udel.edu/extension/pdc/index.htm Virginia Tech Nematode Assay Laboratory Phone: 540-231-4650 115 Price Hall Blacksburg, VA 24061-0331 Fax: 540-231-7477 E-mail: jon@vt.edu Website: www.ppws.vt.edu/~clinic/nematode.php
Questions?