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Apricot fungus (shothole?) infection control - spreading

Posted by melissascop Maryland (My Page) on
Thu, May 21, 09 at 15:47

I have a recently planted home orchard using high density planting (plants are close together and on dwarf rootstock and will be pruned and kept small)-- 6 trees-- 2 apricots (moorpark and early golden), 2 peach, 2 apple.

All were planted in Feb-March (dormant--bareroot plants).

I just noticed that one of the apricots (moorpark) has extensive leaf spots (perhaps shot-hole?). All plants are young. Should I remove the apricot plant to help control the infection or is there some other infection control procedure I should take?

None of the other plants have evidence of leaf problems. I'd prefer to keep the moorpark if it doesn't put the other plants at high risk.


Follow-Up Postings:

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RE: Apricot fungus (shothole?) infection control - spreading

Shothole is widespread in Maryland, all of my trees have a bit of it, so I don't think removing the tree is going to be of any help long-term. Just-planted trees are more susceptible to shot-hole and rains also make things worse. There isn't a lot you can do about shot-hole during the growing season, the main treatment is to spray copper at leaf fall and again just before the leaves come out in the spring. There is a spray called fungonil which can be of some good now if you can find it (its hard to find). It will moderate when the really hot weather comes. I would just leave it until the fall and hit it with copper then.

Scott


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RE: Apricot fungus (shothole?) infection control - spreading

Thank you so much for the information. I'll look at some specialty stores for fungonil. It's good to know that it is something that may be treatable to some extent. I appreciate your time in responding to my post.


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RE: Apricot fungus (shothole?) infection control - spreading

Mellisa, I had horrible shot-hole when I was planting out my orchard and I thought I would never get rid of it. But once I started to do the fall/spring copper I got it under control. With high-density plantings it is very important to keep them opened up since dense trees are much more likely to get diseases. The high-density technique developed in California does not directly work in the east. What it means is you need to keep very few scaffolds on your trees. I have many trees that are Y-shaped (two scaffolds) or just one narrow spindle.

Scott


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RE: Apricot fungus (shothole?) infection control - spreading

Melissa:

You don't say just how close is "close" in your high-density planting, but you may be in for some surprises. It would help to know where you sourced these trees, and whether you know exactly what rootstocks are beneath them.

Some apple rootstocks, such as M-27, M-9, and Bud-9, can properly be defined as "dwarf", but if the apple rootstock is M-7 or any of the other semi-dwarfs, it is a different story entirely. Many mailorder and online nurseries will throw all of these into the same basket, assuming the grower is not interested or concerned with the differences. Often, you cannot trust nurseries to properly define a "dwarf".

Unless peaches are true, genetic dwarfs, they are usually on rootstocks like Lovell, Bailey, or Halford, and these are capable of growing trees well over 12 feet tall with equivalent spread. Once they reach the takeoff point at about 5-6 years, keeping them under control is a big, big job. Peach trees produce best when they are pruned to open centers and allowed to spread out. One good spreading peach tree can produce more peaches than 3 trees that must be constantly pruned to keep them from growing into one another. And the single tree will have fewer disease problems since it is open to light and air.

The same is true of apricot trees, which are normally budded on seedling roostocks. I have apricot trees in my orchard that would have easily reached over 15 feet if I did not regularly prune them down. There are not, as far as I know, any apricot rootstocks that will actually control the growth of these trees in a manner that could be called "dwarfing". The slowest-growing apricot tree I have now is a Puget Gold on a plum rootstock called St. Julian "A", and that is now over ten feet tall with an 8-foot spread, and wants to grow larger.

I know there are many advocates of the "pack'em in" school of fruitgrowing here, but I am not one of them. I would prefer to have one good, stand-alone tree that I can get around to spray, thin and pick easily, and don't have to be concerned about trees growing into a tangled mess. I think they look better too, if aesthetics is a concern.

It is surprising that an apricot tree planted only this spring would develop shothole fungus, and makes me wonder if the tree was not infected when your received it. I would not, BTW, plant Moorpark or Early Golden apricots in Maryland. I had these varieties for over ten years here, and they produced zero. Now I have Tomcot trees, and pick a bountiful harvest of apricots nearly every season. My climate is very similar to yours.

Don Yellman, Great Falls, VA


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RE: Apricot fungus (shothole?) infection control - spreading

Just on the market lately here is a product called Actinovate. It's derived from biological source, is OMRI listed and seems to work fantastic on shot hole. Also listed for use to prevent damping off, root rot, powdery mildew, grey mold , and lawn brownspot. Kinda expensive but use only two teaspoons / gallon spray . Packaged as a powder that has a shelf life of about one year


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RE: Apricot fungus (shothole?) infection control - spreading

I have a question about shot hole fungus. has anyone had any success to slow the spread of shot hole during the growing season with maturing fruit on the trees? These trees were well sprayed with copper during dormant, I biffed on not spraying at the shuck time or shortly there after with a fungiside. Now I have shot hole spreading and a good crop of everything to protect. any ideas or successes? prunepicker


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