I have a 10 year old honey crisp apple tree that get worms each year. The...
I have a 10 year old honey crisp apple tree that get worms each year. The tree is healthy and produces a lot of apples, but almost all of them are bad from worms. I spray the tree with Seven about once a week starting after the blossoms drop, I also put down a granular grub control and always pick up the dead fall. But all my efforts are in vein. See attached example of an apple. Is there a pesticide you can recommend. Thanks for your help! Alan VanHouten Carver, MN
Thank you for the question. How frustrating that you are getting worms in your apples every year even though you are trying hard to do all the right things. Growing apples of good quality is a time and labor intensive activity.
It's a bit hard to tell what the problem may be from one photo but 2 likely culprits are codling moth or plum curculio beetles since you have the damage already this season. If you see worms in the apple, it's probably codling moth. Plum curculio can cause premature apple drop and characteristic scars on the apple surface from the female trying to lay eggs in the hard apple surface. This damage is cosmetic. You will never find plum curculio larvae in apples that mature on the tree because they can't get through the hard flesh. When the apple drops to the ground and softens, larvae can penetrate the flesh and feed. That's why it's so good that you are picking up those fallen fruits
Read these University of Minnesota publications on both pests:
Here is the University of Minnesota's apple pest management calendar. http://www.extension.umn.edu/garden/yard-garden/fruit/apple-pest-management/
It describes when to use certain products as well as what you can do to monitor your trees to make sure you know what pest you are trying to treat. Compare it to how you are managing your tree and make changes as needed.
Good luck and thank you for contacting Extension.