What is that quoted from? I ask because when I was doing a term paper on the effects of LAWN chemicals on soil flora ten years ago (chemicals that actually are meant to go into the ground, as opposed to those that are meant to land on foliage) -- every expert I interviewed, from university entomologist to extension agents, arborsts and turfgrass professors -- said that the chemicals used today do not kill soil organisms. Not even earthworms.

The biodiveristy is affected, meaning there are fewer types of organisms, but the populations are still high -- and again, this was in references to chemicals actually put into the soil.

I was very concerned that lawn chemicals would effectively sterilize the soil, when a U. of IL entomologist chuckled and said, "Listen, if 2,4-D sterilized soil, pineapple growers in Hawaii wouldn't be petitioning the UN for exemptions to fumigate their fields with methyl bromide." Good point.

Anyway, I would be delighted to be dealing with powdery mildew right now. At the moment, I am removing bushes infected with rose rosette disease.

Want causes the "fewer types" of organisms. As they diverted elsewhere?

MulchMama, the full paper is not yet available to me through the university. The wording in a reviewed accepted scientific paper is subject to scrutiny by the reviewers and the editor. This wording is also consistent with what I have read in the scientific literature.

The commercial fungicide that they compared with is Topaz (a penconazole based "azole" family fungicide).

For plants I assume that the greatest concern is whether the Topaz is damaging the mycorrhizal fungi relationship with the plant roots.

"Abstract
In order to quantify the importance of ectomycorrhizal fungi on nutrient uptake from the coarse-soil fraction of a haplic Cambisol (alumic), a microcosm study that allowed for nutrient budgets was designed. Ectomycorrhizal- and fungicide-treated spruce seedlings were grown on isolated and cleaned gneiss fragments (6.3 mm > à> 2 mm) from 90 cm soil depth. The substrate was the only source of Ca, K and Mg. Ectomycorrhizal seedlings showed no signs of nutrient deficiencies and biomass increased significantly compared to initial seedling biomass. Ectomycorrhizal seedlings seemed well adapted to survive on the coarse-soil substrate and acquired Ca, K and Mg from the coarse-soil substrate. Gneiss fragments of the ectomycorrhizal treatment were covered by fine roots and ectomycorrhizal hyphae, as observed microscopically. Fungicide-treated seedlingsâ root development was retarded, and shoot biomass only increased from stored nutrient reserves of the seedlings. The suppression of EcM colonization by the fungicide Topasî apparently caused a root growth inhibiting effect. Furthermore, the extinction of mycorrhiza initiated an increased nitrification and acidification and a consequent nutrient cation release triggered by nitrate in the drainage."

A Google Scholar search with the keywords: penconazole and mycorrhizal fungi

Here is a link that might be useful: link for above