THE amount of positive anthracnose tests in lupins grew seven-fold last year, ccording to the Agriculture Department.
The improved conditions would have played a role but researcher have warned growers to be vigilant.
Department plant pathologist Geoff Thomas said anthracnose was more prevalent in lupin crops than in previous seasons.
"Several crops suffered significant yield damage, however in general, disease levels were not high enough to cause widespread yield loss but will have resulted in infected seed being harvested," Mr Thomas said.
Results from the anthracnose seed infection tests submitted to AgWest Plant Laboratories (APL) support this observation. Approximately 38pc samples tested from the 2003 crops were positive.
Comparatively, approximately 5pc of test from the previous two seasons were positive.
Positive samples have been received from the Northam, Moora, Three Springs and Geraldton regions.
Mr Thomas said the increased number of positive seed tests indicates many seed lots might contain higher levels of infected seed in the coming season.
Mr Thomas said seed infection was the primary method of transfer of anthracnose and could result in significant yield loss due to the early build up of infection in crops.
Another season like 2003, combined with a higher level of infected plants in crops could generate significant yield losses, particularly in high and medium rainfall areas.
"Infected seed poses a threat to all varieties however the risks are greatest in susceptible or moderately susceptible varieties and least in resistant varieties such as Wonga and Tanjil," he said.
"Anthracnose control relies on variety selection, the use of clean seed and thiram seed dressing and reducing or avoiding other inoculum sources, such as blue lupins."
A quantitative DNA based 10,000 seed test is available commercially through APL.
Seed sbmission forms and instructions are available by faxing APL on 9474 2658.
pMore information on the importance of seed borne infection and critical seed infection thresholds is provided with seed test results or via the dpartment website at www.agric.wa.gov.au