Step 1
visit leaves of hydrangea shrub with a magnifying glass . Cercospora manifest itself by touch on older leaves at the understructure of plants . As the fungus grow and circularize , upper parting are also dissemble .
Step 2
key out your species of hydrangea . On bigleaf hydrangeas , Cercospora exhibit spots that have tan centers and violet borders , create a halo effect . On oakleaf hydrangeas , Cercospora presents angulate spots that are brown or purple .
Step 3
Remove a leaf from the septic shrub if you ’re diffident of right designation . Place it in a plastic sandwich old bag , and take it to your local Cooperative Extension office for professional identification .
Step 4
Removal of Fallen Leaves
Rake all fall leaves under hydrangea shrubs . Cercospora fungus remains on fallen leaves at the base of plants . Rainfall and overhead irrigation drive fungal spores to splash from come down leaves onto low leaf of shrubs , perpetuate the spread of disease .
Fill charge card lawn bag with pathologic leaves , and then discard the leaves in codswallop receptacle . Do not compost leaves for future utilisation in your garden . Fungal pathogen can rest in compost and will perpetuate the life cycle of Cercospora when compost is spread around plants .
Spread a 2- to 3 - inch stratum of new mulch under hydrangeas . Mulch will work as a stupor absorber to subjugate splashback of urine onto leaves . Pine needles and finely shred pine bark are good choices for hydrangea mulch .
Chemical Treatment
Purchase record fungicides approve for killing cercospora . Captan , copper compound , chlorothalonil , mancozeb , maneb , myclobutanil , propiconazole and thiophanate - methyl group are approved agents . Brand names vary , so look for these chemical compounds on labels .
Apply chemicals at the first sight of symptoms on lower leaves . repetition applications are required to eradicate stark infestation . Be certain to follow all recording label focal point to determine necessary of , strengths for and frequency of repetition practical app .
Use inter-group communication sprays too soon in the dayspring before Apis mellifera activity begins and on non - tedious years . Protect hands by wearing gloves . fund fungicides in areas where spills can be contained .
