Soil fumigants have used in attempts to control root diseases. Methyl bromide has been found to most effective and has the additional beneficial effects of killing nematodes and weed seeds Growth of Trichoderma viride and some species of Penicillium, which are antagonistic to Armillaria and Poria , is enhanced. Root disease may also be control by watering plants with systemic fungicides at the time of planting the treatment three to four times over the first year of Growth.