Treating Leaf Curl Plum Aphid - Ask Extension
I understand that ladybugs are the primary predators for this aphid species. I can’t do anything about this now, but wanted to make sure that next ...
Knowledgebase
Treating Leaf Curl Plum Aphid #797770
Asked June 25, 2022, 12:19 PM EDT
I understand that ladybugs are the primary predators for this aphid species. I can’t do anything about this now, but wanted to make sure that next spring I was ready. My question is, when do I apply the ladybugs in spring? If it’s too early (cold) won’t they just die off? Also, Do you have an environmentally safe method for applying an insecticide? Thanks
Polk County Oregon
Expert Response
Thanks for reaching out.
Relying only on ladybugs or other predators will not be effective. Like you mentioned, cool spring weather will definitely be a factor. By the time the ladybug population gets established the aphids may already have caused an unacceptable amount of damage.
Here's what I recommend trying: During a dry stretch In February apply a dormant oil spray. This will help smother any aphid eggs that are overwintering in cracks on the branches & buds. Then after the tree has flowered (petals are falling onto the ground) apply another spray of either an insecticidal soap or a neem oil-based product. This should kill any aphids that managed to hatch but before the leaves curl. (The leaves curl around the aphids and protect them from coming in contact with the spray.)
If you still want to try ladybugs put them on when the weather warms up to above 55. Here's more tips on using ladybugs.
Here's some resources for additional reading: Take a look and let me know what additional questions you have.
Relying only on ladybugs or other predators will not be effective. Like you mentioned, cool spring weather will definitely be a factor. By the time the ladybug population gets established the aphids may already have caused an unacceptable amount of damage.
Here's what I recommend trying: During a dry stretch In February apply a dormant oil spray. This will help smother any aphid eggs that are overwintering in cracks on the branches & buds. Then after the tree has flowered (petals are falling onto the ground) apply another spray of either an insecticidal soap or a neem oil-based product. This should kill any aphids that managed to hatch but before the leaves curl. (The leaves curl around the aphids and protect them from coming in contact with the spray.)
If you still want to try ladybugs put them on when the weather warms up to above 55. Here's more tips on using ladybugs.
Here's some resources for additional reading: Take a look and let me know what additional questions you have.
Thank you for getting back to me. I will use your tips next Feb. I wanted to ask you a follow up question. You mentioned “after the flowers have fallen”……the 2 plum trees do not flower….ever since I started cutting them back in mid to late summer. The new growth gets so high, it obstructs the view from our second story deck!?!? Consequently, no more plums. Is there some happy medium between fruiting plum trees and unobscured backyard vistas?
Replacing with semi-dwarf trees might be the answer for this growing situation! Depends on how high your deck is.
Most fruit trees are grafted. The scion (aboveground portion) is a cultivar with the desired fruit characteristics. The rootstock (below ground portion) is different cultivar that has other features. Those features could be disease resistance or dwarfing. With dwarfing rootstocks the fruiting part of the tree doesn't get as tall as it normally would. There are different cultivars used as rootstocks. For plums you might see Mariannna 2624 (Mar2624), Citation, Myrobalan, St. Julian A or Krymsk 1 listed on the tag.
Here is an example of what to look for. In the middle of the page you'll see the list of plums in tan with the rootstocks listed in the next column. Here's another example from different nursery. You can sort by 'tree size' then click on the individual cultivar to find info on the rootstock used. Your local nursery should have similar information available. Where ever you end up buying from definitely do your research. Otherwise you could end up struggling with more full-size trees.
Plums on semi-dwarf rootstocks will still need regular pruning for good fruit development and tree health but shouldn't block the view! Hope that helps!
Most fruit trees are grafted. The scion (aboveground portion) is a cultivar with the desired fruit characteristics. The rootstock (below ground portion) is different cultivar that has other features. Those features could be disease resistance or dwarfing. With dwarfing rootstocks the fruiting part of the tree doesn't get as tall as it normally would. There are different cultivars used as rootstocks. For plums you might see Mariannna 2624 (Mar2624), Citation, Myrobalan, St. Julian A or Krymsk 1 listed on the tag.
Here is an example of what to look for. In the middle of the page you'll see the list of plums in tan with the rootstocks listed in the next column. Here's another example from different nursery. You can sort by 'tree size' then click on the individual cultivar to find info on the rootstock used. Your local nursery should have similar information available. Where ever you end up buying from definitely do your research. Otherwise you could end up struggling with more full-size trees.
Plums on semi-dwarf rootstocks will still need regular pruning for good fruit development and tree health but shouldn't block the view! Hope that helps!
Thank you for your help!
