Gardening season is underway, and you may have questions. For answers, turn to Ask an Expert, an online question-and-answer tool from Oregon State University’s Extension Service. OSU Extension faculty and Master Gardeners reply to queries within two business days, usually less. To ask a question, simply go to the OSU Extension website, type it in, and include the county where you live. Here are some questions asked by other gardeners. What’s yours?
Q: Last year I had to pull out a blueberry plant that had totally died. Its disease started with large swaths of leaves turning brown, dried and crispy. By the end of the summer, it was totally dead. Also last year I had a plant that gave some good berries, but some of the berries were pale and deformed. That plant also had some ruffly leaves, deformed.
I looked those characteristics up online and I believe them to be caused from mummy berry disease. The mummy berry seems to be localized to one plant that is in the middle of four others, all mature plants. I put down compost as recommended to stop any spores that may be lying on the surface. However, I am wondering if I should just pull that whole plant now.
Do you recommend any treatments that will save the plant? Or do you think that the safest procedure would be to pull the plant now? Pulling the plant is what I am leaning towards. If I do pull the plant, do you recommend any other treatments? – Lane County
A: We saw a lot of scorched plants and shriveled berries last summer due to the heat wave so be certain mummy berry is what you are dealing with (early symptoms can also be confused with blueberry scorch virus). With mummy berry, the dried, shriveled infected berries (or mummies) drop to the ground in fall and winter and form apothecia (small mushrooms) that appear in the spring around bud break. Look for the apothecia in spring, and white fungal hyphae in infected green berries for clear signs of the disease (here is a video on how to monitor for mummy berry).
It is difficult to stop the spread of mummy berry, since it is spread by wind, rain and pollinating insects, so management needs to focus on the overwintering stage and cultural controls. Whether you remove infected plants or not depends on whether you want to go to the effort of trying to manage the disease. If you do decide to replant, rotate your new plant to a different area of the garden, and select a resistant cultivar. Some blueberry cultivars are more susceptible to mummy berry than others (Berkeley, Elliot, Earliblue and Dixi are highly susceptible).
Non-chemical control options include harvesting and destroying mummified fruit before it drops to the ground, mulching with 2 inches of Douglas-fir sawdust in the dormant season to prevent the emergence of the apothecia, and destroying any emerging apothecia in spring (can use a rake). There are fungicides that can be used, but fungicides need to be applied between bud break and the end of flowering to protect the foliage and flowers from infection. Begin spraying when the earliest cultivars break bud. You will need to rotate chemicals with different modes of action in order to prevent resistance buildup. For more on mummy berry management, see this article. – Erica Chernoh, OSU Extension horticulturist
Q: Is there anything I can do to keep squirrels from going into my potted plants and digging up the dirt? It appears they are attempting to bury peanuts that someone in our neighborhood has left out for them. – Washington County
A: I recommend creating some tight-fitting “collars” of welded-wire (1/2″ mesh would exclude most digging) for each pot or bed. – Dana Sanchez, OSU Extension wildlife specialist
Cold damaged cherry tree leaves should shed as the season progresses. OSU Extension Service
Q: Where I live there are many old, grafted cherry trees along the streets that give a spectacular show of pink flowers in April. This year was no exception. But now many of them are in evident distress, with many shriveled and brown leaves. I have never seen this before and am wondering what is happening. Perhaps this was a result of our late freak snowstorm? Or is there a pest or diseases running rampant? Can anything be done to help the trees recover? – Multnomah County
A: To me it looks like the first leaf buds of the season to open were damaged by the cold weather we had in April. The newer growth looks fine. The damaged leaves will be shed as the season progresses. The trees should leaf out normally. – Weston Miller, OSU Extension horticulturist
Did this insect cause damage to this apple tree’s leaves? OSU Extension Service
Q: What spray or home recipe do you recommend for apple and pear trees? Please see attached photos of my apple tree. I planted it a year ago and this year it got a lot of insects and I’m not sure why the leaves are getting black. – Washington County
A: The damage on the leaves is likely due to apple scab, a very common disease on apples. This spring has been wet and cold, which favors plant diseases. Here’s some information.
Fungicide treatments for apple scab are done early in the spring when plants are flowering and not recommended at this time of the season. If you choose to treat, follow the instructions at the link above. Lime sulfur is an effective fungicide choice.
The insect to me looks like a syrphid fly larvae that is eating aphids. It’s a beneficial insect. If you were to spray for the aphids, you’d also kill the predators. Soon enough, the aphid populations will die back and I don’t recommend treating at this time. – Weston Miller, OSU Extension horticulturist
