When applied as a seed treatment to

When applied as a seed treatment to naturally infested watermelonseed, AAC00-1ΔhrcC suppressed BFB seedling transmissionsimilarly to AAA 99-2, a strain previously reported to be antagonisticto A. citrulli. Under greenhouse conditions, AAC00-1ΔhrcC seed treatments delayed the onset of BFB symptoms onwatermelon seedlings. Interestingly, we observed better suppressionof BFB seedling transmission in the growth chamber (5.5-foldreduction) than in the greenhouse assay (1.6-fold reduction). Thiswas unexpected because conditions in the growth-chamber assaywere consistently highly conducive for BFB seedling transmission,whereas conditions in the greenhouse (namely, relative humidity)were less conducive. Because plants were allowed to grow for 21versus 12 days in the greenhouse experiment, we concluded thatthe biocontrol efficacy of AAC00-1ΔhrcC declined as the seedlingsmatured. This was likely due to the inability of the mutant to colonizeolder watermelon foliage and compete with AAC00-1 once itentered the pathogenic phase.

When applied as a seed treatment to naturally infested watermelon
seed AAC00-1 Δ, hrcC suppressed BFB seedling transmission
similarly. To, AAA 99-2 a strain previously reported to be antagonistic
to A. Citrulli. Under, greenhouse conditions AAC00 -
1 Δ hrcC. Seed treatments delayed the onset of BFB symptoms on
watermelon seedlings. Interestingly we observed, better suppression
.Of BFB seedling transmission in the growth chamber (5.5-fold
reduction) than in the greenhouse assay (1.6-fold reduction).? This
was unexpected because conditions in the growth-chamber assay
were consistently highly conducive for BFB seedling transmission
whereas,, Conditions in the greenhouse (namely relative, humidity)
were less conducive. Because plants were allowed to grow for 21
.Versus 12 days in the, greenhouse experiment we concluded that
the biocontrol efficacy of AAC00-1 Δ hrcC declined as the. Seedlings
matured. This was likely due to the inability of the mutant to colonize
older watermelon foliage and compete with. AAC00-1 once it
entered the pathogenic phase.