IMPROVEMENT OF THE GERMINATION RATE OF LA MBS LETTUCE SEEDS (VALERIANELLA-LOCUSTA) WITH FUNGICIDE TREATMENT

In lamb's lettuce (Valerianella locusta), seed germination analysis at harvest lime often needs a method to break seed dormancy. However res ults are frequently improved by a fungicide treatment with thiram. The purpose of the study was: (i) to investigate the relationship between seed dormancy, fungus contamination of seed lots and germination impr ovement by thiram, and (ii) to compare the relative efficiency of othe r fungicides on germination and against seed lot contamination by Phom a valerianellae. The results clearly show a close correlation between seed lot contamination by Phoma valianellae and the beneficial effect of thiram on seed germination. They also reveal the very good efficien cy of the new fungicide Prelude. The study was undertaken in order to find agronomic techniques for producing lamb's lettuce seeds free of P homa varelianellae and also for finding a more efficient method to bre ak seed dormancy. However for the time being it seems useful to introd uce in ISTA rules a seed treatment opportunity against Phoma valeriane llae in the official germination test for lamb's lettuce seeds, as has been done against Phoma betae in the germination test for sugar beet.