(Next slide.) That's a close-up view and is the type of thing I was trying to describe to you earlier where the shucks dry up and stick to the nut so that you cannot remove them. Those on the left, of course, would be absolutely no good for commercial purposes.
(Next slide.) Now, I suppose you are all interested in this matter of control. Unfortunately, I must admit that I have not worked on the walnut husk maggots very much in the last 15 or 20 years. You may recall that we had a severe freeze back in 1933 or 1934, which took out quite a lot of our Persian walnuts in Western New York, and only the hardier trees remained. But prior to that time we had been getting numerous complaints, from growers about injury from walnut husk maggots, and we did some work at that time and also worked with the Farm Bureau people in the counties where walnuts were grown fairly commonly. In many cases these Persian walnuts were grown on fruit farms where they also have apples and other fruits. So that in those cases it was not a difficult problem to obtain control. We worked out a program whereby, say, beginning about July the 20th to the 25th, at which time quite a few of the flies would have emerged, if the orchardist, when he was going through with his regular spray operation on his fruit trees, would give his walnuts at least two applications at about two weeks intervals, he'd cease to have a maggot problem. That pretty well solved it, as far as they were concerned. But there were also these other plantings where you'd have just a few trees, or possibly one tree in a back yard, something of that sort, which is a little bit more difficult to control.
Dr. Glasgow and I found that on cherry maggot in the city, while a material like lead arsenate is very effective in a commercial orchard, it's very ineffective for just one little tree in your own back yard, providing your neighbors have some trees and they don't spray them. The reason is very obvious: the flies don't necessarily stay on the same tree. They visit around from tree to tree, they feed on the surface of the leaves or fruit. Therefore, it's possible for them to be over on someone else's unsprayed tree and still come over and lay eggs in the nuts of a sprayed walnut tree before being killed. So you can see that such activity may create somewhat of a problem.
At any rate, the lead arsenate spray of three pounds to a hundred gallons, with or without fungicides, has given good control in the past. That No. 3 combination of lime sulphur and lead arsenate was used west of Rochester here around Hilton where this grower had a commercial fruit planting, but he also had a number of English walnuts. The year prior to the time these trees were sprayed he had about 40 per cent of the nuts infested, and the year these were sprayed the infestation dropped they came down to about one percent. Notice the comment at the foot of the table which states that the trees that were not treated the following year went back up to 20 per cent of the nuts infested. There were about 20 per cent of the trees that had infestation. Of course, the flies moved around enough that the trees became reinfested. It simply brings out the point that unless you have a pretty good-sized planting, you are going to have to spray pretty thoroughly in order to get control, and also, if you only have one or two trees and you have a lot of surrounding shrubbery and a lot of trees, it would be very wise to also spray those, unless they are plums or peaches, which are quite susceptible to arsenical injury. But most things would stand the arsenate of lead, and it would be very desirable, wherever you can, to spray surrounding trees and shrubs close to the walnuts themselves, and in so doing you would get pretty effective control. It is quite possible to use this control method and obtain over 80 per cent reduction in infestation.
I am sorry to say I don't have any information on these newer materials, like DDT, methoxychlor and parathion. You have probably read about all of those in the magazines. Some of the men in our department have done quite a bit of work with these insecticides on the apple maggot in the Hudson Valley and in Western New York and they find, as I mentioned earlier, while it's possible to obtain control of apple maggot, say, with DDT, it requires much more frequent application. In that case, if any of you are orchardists or follow the apple-growing insect problems at all, the first application of the walnut maggot spray should go on at about the time the last cover spray for the coddling moth goes on for the first brood. That sounds a little involved, but from the calendar point of view it would be about July 25th in Central or Western New York. Normally, with us here the cherries are being harvested by about July 15th, sometimes a little earlier, but at any rate, that's the time the flies usually begin to emerge.
We have what we call a pre-oviposition period of about two weeks, during which time the flies are not laying any eggs in the shucks and are moving around feeding. Of course, that is the time you have to get this spray material on, before they have punctured the nuts and deposited eggs inside.
I think, unless there are questions, that's all I have to say.
A MEMBER: You recommend No. 3 to be used?
DR. GAMBRELL: Lead arsenate at 3 lbs./100 gallons and 2 gal. of lime sulphur would be an effective insecticide-fungicide mixture. I have used both the wettable sulphur and lime sulphur, as shown here, without any injury to foliage. Sometimes, as you know, if it's real hot, like today, sulphur could cause you a lot of foliage injury. Dr. MacDaniels will certainly bear me out on that.
PRESIDENT BEST: Now I think Joe McDaniel has a little idea here he wants to introduce at this time.