We have started to see a few inquiries about this phenomenon so far this spring. It's possible, perhaps even likely, that stress from the mildew infection, or outright infection of the dormant buds by the mildew, caused their loss for this flowering season. Unfortunately, even if we would suggest a preventative fungicide spray in this scenario (which we rarely do, given sprays can have detrimental impacts on other organisms, plus timing needs to be fairly precise), it's already too late to apply a product now as the infectious period has already begun. For example, on other trees that are blooming poorly due to deformed and discolored petals, we have seen clear signs of fungal infection (in such cases, a different but equally-disfiguring fungus). If you decide to try spraying anyway, you'll likely need a professional applicator (such as from a landscape company or an arborist) to make the treatment(s), given the size of the tree and difficulty in getting good coverage with homeowner-available equipment and fungicide products. If any preventative treatment window remains at this point, it is rapidly closing. (A lot of above-ground infections occur in spring, even if symptoms don't manifest for weeks or months afterward.) As was likely brought up last year when the tree was diagnosed, fungicides don't cure infection, they only help to suppress or prevent infection, so an ill-timed or ineffective treatment can still result in issues later in the season.

All you can do at this point is to keep the tree in general good health by minimizing further stress, which usually just means irrigating well (as needed) during dry spells in summer and autumn. This tree doesn't seem to have a protective mulch ring encircling the trunk to minimize the risk of contact with mower equipment, so make sure any mowers use caution to avoid bark injury, as the resulting damage can either be serious in and of itself, or make the tree much more vulnerable to Dogwood Borer and other ailments that cause canopy dieback.

Dry autumn weather can impact flower bud survival on plants which flower in spring, as such buds develop the summer/autumn prior to when they open. Since area rainstorms can be patchy, if your local weather tended to be dry last season, and the tree's root zone wasn't irrigated (or at least monitored) periodically, perhaps any buds that were otherwise unscathed succumbed between then and the end of winter. In this scenario, the tree may regain good flowering ability the following year, assuming the conditions causing plant stress don't repeat themselves.

Miri

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