SEED TREATMENT FOR THE CONTROL OF SPHAEROTHECA-FULIGINEA IN MUSKMELONSEEDLINGS

The effects of powdery mildew (caused by Sphaerotheca fuliginea) on mu skmelon seedlings and the efficacy of seed treatment with systemic fun gicides were examined under controlled environmental conditions. The f resh weight of seedlings infected with powdery mildew was substantiall y less than that of uninoculated seedlings 5 weeks after inoculation, and the inoculated seedlings shrivelled 1 week later. The fungicides f enarimol and triadimenol applied to the seeds did not affect germinati on and suppressed powdery mildew effectively when applied at a rate eq uivalent to 8 g fungicide product per kg seed. Under conditions modera tely conducive to the pathogen, fenarimol markedly reduced disease sev erity and its effect when applied as a seed treatment was as effective as foliar treatment. When conditions were highly conducive to the pat hogen, seed treatment with fenarimol was not effective. Development of powdery mildew and efficacy of the seed treatments were related to so il type: disease developed earlier and more intensely on seedlings gro wn in sandy soil than those in organic medium, and seed treatment had a more pronounced effect on seedlings grown in sandy soil. The results indicate that fungicidal treatment of muskmelon seeds may offer an ad equate means of reducing powdery mildew infections on seedlings.