[nafex] FW: Detecting Plum Pox Virus

Lon J. Rombough lonrom at hevanet.com
Wed Jun 21 12:45:43 EDT 2000


This item is one of the news releases and story leads that ARS Information
distributes on weekdays to fax and e-mail subscribers. You can also get the
latest ARS news on the World Wide Web at
www.ars.usda.gov/is/pr/thelatest.htm.
* Feedback and questions to ARS News Service via e-mail: isnv at ars-grin.gov.
* ARS Information Staff, 5601 Sunnyside Ave., Room 1-2251, Beltsville MD
20705-5128, (301) 504- 1617, fax (301) 504-1648.
----------
From: "ARS News Service" <isnv at ars-grin.gov>
To: "ARS News List" <ars-news at ars-grin.gov>
Subject: Detecting Plum Pox Virus
Date: Wed, Jun 21, 2000, 6:37 AM


STORY LEAD:
New Survey Method Adapted to Detect Plum Pox Virus

___________________________________________

ARS News Service
Agricultural Research Service, USDA
Jesús García, (301) 504-1627, jgarcia at ars-grin.gov
June 21, 2000
___________________________________________

A new sampling method to more accurately detect plum pox virus (PPV) has
been adapted by Agricultural Research Service scientists. This method will
be used in the U.S. Department of Agriculture's $1.4 million national PPV
surveillance program. ARS is the USDA's chief research agency.

PPV was first detected in 1999 on peaches grown in an Adams County, Pa.,
orchard. This viral disease infects stone fruit species including peaches,
plums, apricots and nectarines, as well as almonds. PPV infestation produces
blemished, misshapen fruit and causes fruit to drop prematurely. It can even
prevent a tree from bearing any fruit at all. The value of U.S. stone fruit
production was $1.3 billion last year.

ARS plant pathologist Timothy R. Gottwald, with the U.S. Horticultural
Research Laboratory in Ft. Pierce, Fla., and Gareth Hughes with the
University of Edinburgh in Scotland, have adapted the hierarchical sampling
(HS) strategy they developed for citrus tristeza virus to more accurately
sample large areas for PPV.

Previous sampling methods used for citrus and other crops are based on the
number of infested soil samples, disease lesions on a leaf, proportion of
diseased fruit or the number of insects found on each plant.

The problem with using these strategies for PPV is that the amount of the
disease in any given tree cannot be quantified. A PPV-infected tree may be
showing many symptoms or very few and still be entirely infected.

HS also relies on the theory that it's possible to predict disease in one
location by sampling at another. By sampling only 6.25 percent of the trees
in a given orchard in groups of four trees--the location of the trees in the
orchard is critical--and crunching the numbers, scientists are able to accur
ately predict the incidence of infection in the whole orchard.

After performing thousands of simulations, Gottwald and Hughes have shown HS
to be much more accurate at detecting plum pox virus infestation than other
sampling methods.

___________________________________________

Scientific contact: Tim R. Gottwald, ARS U.S. Horticultural Research
Laboratory, Ft. Pierce, Fla.; phone (407) 897-7347, fax (407) 897-7309,
tgottwald at ushrl.ars.usda.gov.
___________________________________________
This item is one of the news releases and story leads that ARS Information
distributes on weekdays to fax and e-mail subscribers. You can also get the
latest ARS news on the World Wide Web at
www.ars.usda.gov/is/pr/thelatest.htm.
* Feedback and questions to ARS News Service via e-mail: isnv at ars-grin.gov.
* ARS Information Staff, 5601 Sunnyside Ave., Room 1-2251, Beltsville MD
20705-5128, (301) 504- 1617, fax (301) 504-1648.




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