We got a couple of good questions in this week for Don & John. They answer both below. And remember, if you have a question for these guys, drop them an e-mail: firstname.lastname@example.org.
Dear Don & John,
An apple tree on my block is 20-25 years old, pretty much neglected, but has a good crop of apples. I haven’t looked at it closely this spring until today, and was dismayed to see that the apples are all junk – see the photo.
What is the cause of this distortion? The leaves generally look OK, though there are a few curled and gray.
What can I do to help this tree?
The photo is great and always helps us provide a more accurate diagnosis. We think there are a couple things going on with your apples.
First, the spots on your apples are probably due to “scab” – a varying collection of fungus. The fact that the apple tree is older and has been neglected doesn’t help, but the wet weather probably had something to do with this as well, giving the fungus more time to establish itself on the fruit.
While problematic, there are organic solutions. The first step is to remove all old leaves from beneath the tree in the fall and put them in the yard waste container, or bury them. Prune out affected twigs, which bear small, blister-like pustules, and put them in the yard waste. Do both of these things in late winter or early spring, before growth begins in the tree.
There are also several organic spray options including sulfur, lime-sulfur, or Bordeaux mixture (copper sulfate plus lime) applied early in the growing season. These are readily available at most nurseries. Spray as soon as the buds show green. And since scab likes damp weather, spray every week until midsummer if the weather is dry. If the summer is wet, spray until 30 days before harvest.
The dimpling on the apples is more difficult to figure out, but it’s most likely a pollination problem – which is a more difficult problem to solve this season. It would be good if you get a lot of bees or other pollinators, as that would help ensure good pollination. Otherwise, next season when the flowers are blooming, take a small brush and a container, shaking some pollen free from the flower, and then using the brush to then apply it to other flowers.
Hope that helps and thanks for writing in.
Don & John
Dear Don & John…
I was cleaning up the ground and fertilizing some of the fruit trees this weekend and I noticed something really odd. All of the plum trees are acting like it’s fall. Several species, all very mature and prolific full-sized trees, have started yellowing and dropping their leaves. 50-60% of the leaves seem to have turned yellow almost overnight. The leaves have brown spots and drop in droves at a simple shake of a branch. I looked for signs of mold or insect damage, but didn’t see anything obvious. They just act like it’s fall.
None of the other fruit trees (cherries, apples, pears, fig) have this issue, though all are suffering somewhat from the weird weather.
Does this have to do with the funky weather we’ve been having? Please help!
You did all the right things in checking what you did. Those are good steps.
And while plum trees in general aren’t producing as much as they did last year, we don’t think the weather is the culprit here, but rather some sort of fungal infection – but it’s difficult to tell without actually seeing the leaves ourselves.
Our best guess is that the fertilizer might be the trigger here. Fruit trees in the Pacific Northwest tend not to need too much fertilizer beyond specific nutrients. But too much nitrogen can spur excessive growth, leaving the tree susceptible to fungal infections.
So we suggest holding off on the fertilization for now and seeing what impact that has on the tree in a few weeks. With all fungal infections, it’s a good idea to pick up all the fallen leaves and put them in the yard waste bin – not your home compost or the disease can spread there.
While you might not get a good crop this year, you can most likely improve the quality of the tree health for next year. In the fall, the tree could benefit from a good pruning – targeting the parts of the tree that were infected this year. This should help the tree produce new growth in the spring.
Fungal infections also benefit from various sprays. Because we can’t identify which fungal infection your tree might have, we suggest bringing in a leaf sample to the Center for Urban Horticulture on any Monday from 4pm – 8pm. They have experts on hand who should be able to more accurately identify which fungus is affecting your tree and then recommend the appropriate organic spray – which would be applied next spring.
Hope this helps and thanks for writing in.
Don & John