by Connie Oswald Stofko
Here are updates on three diseases and one pest: downy mildew on impatiens, tar spot on maple leaves, late blight on tomatoes and potatoes, and the brown marmorated stink bug.
Maybe you’ve been dealing with these issues for years, or you might be noticing one of these for the first time. John Farfaglia, extension educator with Cornell Cooperative Extension in Niagara County, gives us updates.
The good news is that it didn’t hit some plants until the fourth week of September, according to Farfaglia. It usually affects plants in August, and he got a call as recently as last week.
“I thought to myself, ‘It’s almost October,'” Farfaglia said. “That’s pretty late in the year. It’s a lot better than having it show up in August.”
Research is continuing on creating new strains of impatiens that are resistant to downy mildew, he said.
In the meantime, there are many alternative plants you can choose for shade:
- Impatiens are dying; choose alternative shade plants instead
- Gardeners make substitutes for impatiens on Garden Walk Buffalo
- Shade gardeners: new ‘Bounce’ may be good alternative to impatiens
Farfaglia has noticed more calls about tar spot, which shows up as black circles on maple leaves.
“That makes sense because we had a wet spring,” he said.
There’s good news and bad news with tar spot. The bad news is that it is very ugly.
The good news is that it’s a cosmetic issue, but not a health issue for the maple tree, Farfaglia said.
Late blight has been making its way across Western New, and it was confirmed a couple weeks ago in Niagara County.
“It might not be in every single garden, but it’s out there,” Farfaglia said.
Late blight is a serious disease that can kill tomato and potato plants in just one week. It’s best known for causing the Irish potato famine.
Read more about late blight here and what steps you should take to decrease the chances of it spreading.
Brown marmorated stink bug
Farfaglia said he hasn’t gotten as many questions about brown marmorated stink bugs this year.
“Maybe people are getting used to them,” he said.
It may also be possible that they haven’t been out in full force yet. Last year it was the middle of October when I saw them in large numbers at my house. Right now, we’re seeing just one or two at a time.
Brown marmorated stink bugs aren’t dangerous to people; they’re just ugly and annoying in your house. They make a loud noise when they fly and thump when they land. When you squish them, they stink.
They enter homes in the fall looking for a place to hang out during the winter. They don’t do any damage in your house, and in the spring they go outside to mate.
Brown marmorated stink bugs might be more of a problem in your garden because they feed on a wide range of plants. See a list of plants here that they can feed on.
There doesn’t seem to be an increase in agricultural damage from brown marmorated stink bugs, Farfaglia said.
“That might be a good sign,” Farfaglia said, “or it might be that it will just take more time” until their numbers grow to a level where they will cause damage. “We’ll find out.”