Organic Apples (Pests in the Orchard)

Organic Apples (Pests in the Orchard)

Part of Ep. 802 Organic Gardening

Join UW-Extension Entomologist, Dan Mahr as he discusses the challenge of raising apples organically.

Premiere date: Jun 24, 2000

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
Up to now, we've been talking about growing vegetables organically. Now we're going to look at fruit, specifically apples. But according to UW-Extension Entomologist, Dan Mahr, apples are a real challenge. Why is that?

Dan:
Shelley, that's because there are maybe 40 or 50 different types of insects that attack apples.

Shelley:
Wow.

Dan:
As well as a good handful of different types of diseases.

Shelley:
So, is there anything we can do?

Dan:
There is. Probably the first thing that we need to do is to lower our expectations and not expect to have 100 percent perfectly red shiny fruit. This is an example. This damage was caused by a little caterpillar called a leaf roller.

Shelley:
It looks terrible.

Dan:
It looks terrible now, but that damage is not going to increase at all.

Shelley:
It's going to stay that size?

Dan:
It's going to stay that size. As the fruit grows, it will end up being a perfectly good fruit at harvest time, except for a little scar on the surface. And we can use that for eating, for cooking or whatever.

Shelley:
So, it's just cosmetic. Just cut it off.

Dan:
A cosmetic injury in this case, yes.

Shelley:
Just don't expect perfection. Okay.

Dan:
That's right.

Shelley:
What else?

Dan:
One of the things is there are very serious diseases that attack apples. One in particular, called the apple scab, is caused by a fungus.

Shelley:
These little spots, right here?

Dan:
These little spots don't look much right now, but these are living colonies of fungi. And they are going to continue to grow as the season progresses. And by the time we get to harvest, these fruit will look pretty bad.

Shelley:
Are they usable at all?

Dan:
They may be usable. But in some cases, they may be completely unusable.

Shelley:
What can we do about it?

Dan:
There are some really great disease resistant apple varieties available to us. We can plant those varieties called Jonafree, Redfree, Liberty. These are available through a lot of the garden centers. And we don't have to worry about this disease anymore.

Shelley:
It's not a problem at all?

Dan:
Not a problem at all.

Shelley:
This is good, then. Keep going. What else can I do?

Dan:
Well, one of the things that we can do is called sanitation, which is getting rid of the sources of infestation for these various insects and diseases. One example is down here under the tree. We see that we have several apples that have fallen off the tree. And these apples have actually had eggs laid in them by a variety of insects. They don't look bad right now, but the insects will breed inside these apples and then they will go back in the tree, either this year or next year, and reinfest the tree.

Shelley:
So, by leaving them here, they're just hanging around their food source. They're going to go right back up the trunk again.

Dan:
That's right. So, anytime during the course of the year, from now until harvest time, whenever there are fruit falling off the tree onto the ground, we should pick those up and destroy those right away.

Shelley:
Is that the same reason I'm getting rid of the mummified fruit that's been hanging on my branches since last year?

Dan:
Absolutely. That can be a source of infestation for either insects or diseases for next year.

Shelley:
Anything else I should do?

Dan:
Yes, one of the things that we need to think about is where all these insects are coming from. They're coming from wild trees or abandoned trees. For example, wild plums or wild cherries that oftentimes grow in the woods or the fence rows are a good source of infestation for many of these insects to come into the orchard.

Shelley:
So, really look around-- what my neighbors might be growing, what's on the edges-- before I start planting.

Dan:
That's absolutely right. If you can deal with those wild trees, that'll take care of the problem.

Shelley:
Is there anything I can do if some of insects do get into my apple trees and my backyard?

Dan:
Absolutely. There are some good non-chemical things that we can do. I'll show you a way that we can trap to get rid of apple maggot or railroad worm.

Shelley:
Great. Dan, from a distance, it looks like we have a really fine crop of apples here. But when I get closer-- what are these?

Dan:
These are actually traps designed to trap probably the most important pest of home apple production, which is called the apple maggot fly, also known as the railroad worm. And basically, what we have here is tricking the fly to come to this, thinking that it's a ripe apple. About the first of July, we would hang these in the trees. And we would paint them with a sticky material, which is called Tangle-Foot or Tangle-Trap. And then, when the insect lands on it, it gets permanently stuck to it. It will die there without actually laying eggs in the real fruit.

Shelley:
So, it's not bothering the real apples, just the fake ones. Do we leave these baggies on?

Dan:
Yes, that's just an easy, convenient way of cleaning them off. When we have to change them, we just take the plastic bag off and put a new plastic bag on.

Shelley:
What is this little vial, right here?

Dan:
Well, this is part of what makes it work, also. This is a fruit smelling odor. And it actually attracts the flies, thinking that it is ripe fruit that they're going to.

Shelley:
So, this is a lure.

Dan:
It really lures them in. This is an important part of the trap.

Shelley:
How many would I need?

Dan:
Normally, to get very good control, we would hang one of these for every 100 fruit on the tree.

Shelley:
I have no idea. How much fruit will a tree bear?

Dan:
A large tree can bear thousands of fruit.

Shelley:
Oh, wow.

Dan:
But normally speaking, we recommend using dwarf trees for home apple production anyway, because most people don't need thousands of fruit. A few of these on a dwarf tree or a small tree would do a very good job.

Shelley:
That's great. I can deal with something like that. It's effective?

Dan:
Yes, it's quite effective.

Shelley:
Where would I get these?

Dan:
These are available through many of our garden supply catalogs, and also some of the better garden centers carry these.

Shelley:
I always hear that the insects for apples as the big three. This is obviously one of them. What are the other two?

Dan:
The other two are called plum curculio, which is a beetle, and codling moth. This fruit has actually been damaged by plum curculio. Those little crescent shaped scars that are on the fruit are where the eggs were laid in this fruit. Normally speaking, these fruit would fall off the tree on the ground. But if they continued to mature, they would be very, very lumpy and deformed at harvest time. And in many cases, completely unusable.

Shelley:
Wow. And what about the codling moth?

Dan:
The codling moth is the proverbial worm in the apple.

Shelley:
Oh, the big, ugly one!

Dan:
That's right. It gets right in the center of the fruit and causes the fruit to decay from the inside out. Both the plum curculio and codling moth are very difficult to control with organic methods. We can use some of the conventional organic insecticides, such as Rotenone or Pyrethrum. But they really don't do a very good job against these particular insects and they have to be used very frequently throughout the growing season.

Shelley:
It sounds like we really need to know what we're doing to control these last two guys.

Dan:
That's right. These are a real serious problem that's going to be a little bit difficult. But the other things that we talked about, we can generally get pretty good control with organic methods.

Shelley:
So, there's hope. Just follow instructions. Where do we learn more about this, then?

Dan:
The UW-Extension has several publications on growing apples and controlling apple pests.

Shelley:
Thanks a lot, Dan. And if you're having problems with apples, consider pears and plums. They don't seem to have quite the same problems.

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