Articles
SOME FACTORS THAT LIMIT THE USEFULNESS OF ELISA RESULTS IN EFFORTS TO CONTROL SPREAD OF RUGOSE MOSAIC DISEASE IN SWEET CHERRY ORCHARDS.
Article number
130_41
Pages
242 – 242
Language
Abstract
Rugose mosaic disease (CRM) of sweet cherry (Prunus avium) which is caused by strains of Prunus necrotic ringspot virus (NRSV) creates economic problems for Washington growers by delaying fruit maturity.
As the virus is transmitted through pollen, removal of infected trees before bloom could greatly reduce intraorchard spread of this disease.
Earlier I described an ELISA procedure for detecting CRM strains in dormant flower buds and preliminary evidence suggested that the procedure could be used to identify CRM-diseased trees during the winter months prior to flowering.
During the past two years more than 20,000 trees from over 100 orchards have been tested by ELISA. Many of these have been observed subsequently for symptom development.
In about one-half of the orchards examined early identification and removal of infected trees appears to be a practical approach to disease control.
However, in nearly one-half of the orchards we found situations which severely limit this approach as follows: 1) The main pollenizer varieties were infected but expressed no fruit symptoms.
Consequently growers were reluctant to remove infected but productive trees. 2) In several orchards variant NRSV types were encountered that resemble CRM strains in serological tests but which caused no fruit symptoms on "Bing", the major fresh fruit variety.
Again growers were reluctant to remove productive trees until fruit symptoms appeared. 3) A few CRM isolates were found that were not detected by ELISA using a single antiserum.
Because these situations occur frquently, it is now considered impractical to recommend tree removal solely on the basis of winter ELISA tests.
As the virus is transmitted through pollen, removal of infected trees before bloom could greatly reduce intraorchard spread of this disease.
Earlier I described an ELISA procedure for detecting CRM strains in dormant flower buds and preliminary evidence suggested that the procedure could be used to identify CRM-diseased trees during the winter months prior to flowering.
During the past two years more than 20,000 trees from over 100 orchards have been tested by ELISA. Many of these have been observed subsequently for symptom development.
In about one-half of the orchards examined early identification and removal of infected trees appears to be a practical approach to disease control.
However, in nearly one-half of the orchards we found situations which severely limit this approach as follows: 1) The main pollenizer varieties were infected but expressed no fruit symptoms.
Consequently growers were reluctant to remove infected but productive trees. 2) In several orchards variant NRSV types were encountered that resemble CRM strains in serological tests but which caused no fruit symptoms on "Bing", the major fresh fruit variety.
Again growers were reluctant to remove productive trees until fruit symptoms appeared. 3) A few CRM isolates were found that were not detected by ELISA using a single antiserum.
Because these situations occur frquently, it is now considered impractical to recommend tree removal solely on the basis of winter ELISA tests.
Authors
G.I. Mink
Keywords
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