05/27/2026
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Question – “I have 4 Blueberry bushes that have been significantly underperforming.”
Answer- Your blueberry bushes are showing blueberry stem galls, which are caused by the stem gall wasp (Hemadas nubilipennis). These swollen growths interrupt sap flow and weaken everything above the gall, which explains the poor performance you’re seeing. The best approach is to prune out every gall before budbreak, cutting several inches below the swelling, and destroy the prunings so the insects cannot emerge in spring. For prevention, keep the plants vigorous and less attractive for egglaying by maintaining an open canopy, raking and removing leaf litter to reduce secondary fungal stress, mulching with clean pine bark, and keeping soil pH between 4.5 and 5.2. A quick winter inspection each year to remove new galls is the most effective longterm protection, and most bushes rebound within a season or two once infested canes are removed.
Rotate your crop to a new location in your garden and do not plant potatoes in the former location for at least three years out of potatoes.
This problem can also be caused by certain fungal diseases such as black spots, but most commonly it results from physical damage. To prevent black spots, handle potatoes gently during harvest and storage, avoid dropping them, and store them in a cool, dark, well-ventilated place.
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