How should I treat my pear tree for fungus? Why are the pears cracked?

Question:

I have a pear tree in my yard that I keep meaning to treat for fungus. Its branches hang over blueberry bushes and an herb garden. This always makes me hesitant, wondering whether treating the pear tree will hurt the other plants. What advice do you have about that? I assume that I missed the boat this year on my timing. Look at all the pears it’s producing. Unfortunately most of them are cracked and pockmarked.

Answer:

Jonathan Foster, Home Horticulture Outreach Professional

So, let’s tackle two separate issues:

1) Re: fungicide safety for blueberries and herb garden. I think you should be fine applying treatments for pear scab, though I would take care not to spray any more than is absolutely necessary (a good practice in general, honestly) and to always wash the berries, pears, and herbs very well before using. The three primary fungicide recommendations for pear scab are somewhat common garden fungicides, so I’m not super concerned over any damage to the plants and am more concerned with simply making sure you don’t ingest any of it when it comes time to eat them. Because of the tree’s size and proximity to other plants, you might consider contacting a ME-licensed pesticide applicator for further evaluation of the location and application of the treatment.

2) Re: pear trees issues. It does appear to have some pear scab on the fruits, especially on the right side of the image, so it is probably worth treating per the information in that link. However, the pronounced cracking of the fruit is more likely to be an issue of variable irrigation–too much or too little water can create an imbalance between the growth rates of the interior and exterior of the pear fruit, leading it to split. With the rain we’ve had this year, you’re probably getting fruits that are swelling faster than the skin can accommodate. If you search “pear fruits cracking and splitting,” you should find some images that look familiar (one example here). Unfortunately, there isn’t much you can do with excessive rainfall, but it can be caused by insufficient rainfall, too, so be on the lookout in the future to try to keep the pear as consistently watered as possible. I reached out to our tree fruit specialist, Dr. Renae Moran, for any other thoughts and she offered the following: “Pear scab, too much soil moisture and possibly boron deficiency. Foliar analysis will diagnose the boron deficiency. The attached file can be submitted with a leaf sample. They cost $30.” I will attach the form in case you decide you’d like to have the tree tested for sufficient boron.

Happy gardening.