Application method and growing medium affects the response of cucumber seedlings to inoculation with Trichoderma harzianum

Cucumber seeds were inoculated at sowing with a mixture of seven isolates o f Trichoderma harzianum, previously observed to confer plant growth promoti on in commercial horticulture. The Trichoderma mixture was applied by three different methods: spore-coated organic pellets, a dried biomass powder, o r seed coating. These were added to three different growing media: sterile potting mix, field soil (naturally containing a Pythium sp.) or field soil drenched with captan. The number of healthy cucumber seedlings was recorded after 8 days. There was no effect of inoculation in potting mix. The numbe r of healthy seedlings was lower in the untreated field soil than in the so il treated with captan. The numbers of healthy seedlings were lower in the pellet and dried biomass treatments than in untreated field soil, but with seed coating, the numbers of healthy seedlings were not significantly affec ted. The effect of st:ed coating was tested again, with the isolates of T. harzianum applied individually and as a mixture to field soil. There was no significant effect on the number of healthy seedlings compared with contro ls in any Trichoderma treatment.