I’m not familiar with trichoderma, but did some quick research. Trichoderma appears to be a soil fungus that affects plant roots, not a leaf fungus. If applying to the leaves, I don’t think mixing trich. vir. with neem oil will give the results you want. It looks like trich. vir. should be mixed into the soil to kill such soil fungus. My recommendation is to use neem oil on leaves and trich. vir. in the soil. Test a single plant or small area first though, so you can test the effects on your plants. :)