Soil Inoculation Assessment

Yesterday I assessed my soil inoculated plants and noticed some Phytophthora symptoms, however it has only been 2 weeks and it seems to me to be rather quick for such advanced symptoms to develop. Looking closer at this example in the annotated photo you can see the flagged branch with wilted, necrotic, and curled leaves, and the branch itself is also very dark in colour and necrotic. I feel that it is possible that these plants were not free from infection with Phytophthora when I received them from the grower and now that they are in my irrigated plot the conditions are ideal for the disease to develop. If you look closely it looks as thought a branch has been removed, possibly due to infection, to make the plants look good for sale but the inoculum was still present and has re-emerged in the wet conditions I have put the plants in. Alternatively, it is possible (and preferred) that the pathogen I inoculate the soil with (P. cactorum) has been splashed up onto this lower branch and infected it, or that the roots have become infected and thus cut water supply off to this first branch, causing it to wilt and die (expressing foliar symptoms caused by a root problem). In order to determine what is going on here I will have to try to isolate the pathogen from the margins of this necrotic tissue and grow it in culture to sequence it and identify what species it is. If it is what I applied to the soil then this is great news, if not it is contamination and not good news at all.