Trees, Fruits and Flowers of Minnesota, 1916 Part 27

Mr. Stakman: Did the whole leaf turn brown?

Mr. M'Clelland: Yes, sir, the whole leaf turned brown and came off.

Mr. Stakman: How strong did you use the lime-sulphur?

Mr. M'Clelland: Not very strong.

Mr. Stakman: If you use very strong lime-sulphur you sometimes get such an effect on both plums and apples. Sometimes the leaves fall, and almost immediately you get a new crop of leaves.

Mr. M'Clelland: This was in August.

Mr. Stakman: There was a perfect crop of new leaves?

Mr. M'Clelland: Yes, sir.

Mr. Stakman: My only suggestion would be that you used the lime-sulphur too strong. That might account for it.

Mr. Sauter: I never sprayed until this year. I tried it this year and with good results. I sprayed my apple trees at the same time, and I sprayed the plums with the same thing I sprayed the apple trees with. I had nice plums and nice apples; last year I had hardly any.

Mr. Stakman: What did you use?

Mr. Sauter: Lime-sulphur and some black leaf mixture. I used it on the plum trees and the apple trees, and afterwards I used a.r.s.enate of lead.

Mr. Stakman: You didn't get any injury to the plum trees?

Mr. Sauter: No, sir, we had nice plums.

A Member: I have seventeen plum trees, and I have only sprayed with kerosene emulsion and the second time put in some Paris green, and I have never seen any of the brown rot, but there have been a good many of the black aphids on the plum trees, on the end of the branches. I cut them off and burned them. I didn't know whether that would be the end of it or not.

Mr. Ruggles: Why don't you use "black leaf 40," 1/2 pint in 50 gallons of the spray liquid. It can be used in combination with a.r.s.enate of lead and lime-sulphur or a.r.s.enate of lead and Bordeaux mixture.

If you wash them with black leaf 40 it will kill all the aphids. I did that myself this summer.

A Member: Please give us a little better explanation of what black leaf 40 is.

Mr. Ruggles: It is an extract of tobacco that is for sale by wholesale drug companies and stores, or you can get it from Kentucky, from the Tobacco Products Company, at Louisville, Ky., or Gra.s.seli Chemical Co., St. Paul. I am not advertising, Mr. President, but they will send you a small package for seventy-five cents, about half a pint. Of course, that looks kind of expensive, but it will go a long way. I think possibly it is the best thing we have to combat lice.

Mr. Stakman: Plum pocket is caused by a fungus which is supposed to infect mostly when the flower buds are just beginning to swell, especially in cold, wet weather. Plum pocket causes the fruit to overgrow and destroys the pit, and big bladder or sack-like fruits are produced instead of the normal fruit. The fungus that causes it gets into the twig and is supposed to live there year after year. Therefore pathologists usually recommend cutting out and burning affected branches and even trees that bear pocketed plums several seasons in succession.

Our experiments with plum pocket have not extended far enough to enable me to say anything definite about it.

Mr. Hall: With us in western Minnesota this year this plum pocket got all the plums that the frost didn't get. If we were to cut off the twigs we would have to chop off the trees.

Mr. Stakman: When a tree becomes so badly infected that practically all of the branches produce pocketed plums year after year you can't expect very much normal fruit. Sometimes you might get some, but usually not very many.

Mr. Graves (Wisconsin): Do you use your black leaf 40 in conjunction with your Bordeaux or lime-sulphur?

Mr. Ruggles: Yes, you can.

Mr. Graves: Doesn't it counteract the result?

Mr. Ruggles: No, it does not.

Mr. Stakman: I used this year lime-sulphur and black leaf 40 together.

Mr. Graves: You say you got the same results from black leaf 40 in that mixture?

Mr. Stakman: It killed the plant lice; that is all I wanted.

Mr. Graves: We had some experiences that indicated that black leaf counteracted the other results.

Mr. Stakman: Yes, sir, I think that has been the impression, but I think there have been some experiments more recently to show that the black leaf 40 can be used in conjunction with other sprays without counteracting their results.

Mr. Richardson: Did you ever know the plum pocket to come unless we had cold weather about the time of blossoming and lots of east wind?

Mr. Stakman: Yes, a little; I have seen it mostly when there was cold weather, however, and as I said before it usually isn't so serious unless there is cold, wet weather.

Mr. Richardson: I settled out in Martin County, Minnesota, in 1866, and in all my experience I never saw plum pocket unless we had the right kind of cold weather at the time of the blossoming. I had my plums all killed and destroyed one year and never did anything for it, and when we had the right kind of weather I never had any trouble.

Mr. Stakman: When you have cold, wet weather, as I mentioned before, infection takes place much more rapidly than it does at other times.

There is some evidence to show that the fungus lives in the twigs and that affected ones should be cut out.

Mr. Richardson: Yes, but these didn't bear any for four or five years, and when we got the right kind of weather I got good plums.

Mr. Norwood: My experience is something like this man's. I have had my plums killed off as many as five years with the plum pocket and then had a good crop of plums. I sprayed with lime-sulphur.

Mr. Stakman: When did you spray?

Mr. Norwood: I spray just before the buds open.

Mr. Stakman: The flower or leaf?

Mr. Norwood: Flower, and then I spray when the plums are well started, just before they begin to ripen.

Mr. Stakman: Were you spraying for the pocket or brown rot?

Mr. Norwood: I used lime-sulphur and a.r.s.enate of lime.

Mr. Stakman: Of course, spraying after buds open wouldn't do any good for the plum pockets at all.

Mr. Norwood: I spray mainly for the brown rot, and I have pretty good luck.

Mr. Cashman: Have you had any experience in using orchard heaters to save plums in cold nights?

Mr. Stakman: I will ask Mr. Cady to answer that.

Mr. Cady: No, I haven't tried to use them.

Mr. Cashman: We tried it this year, and we saved our plum crop. We have tried it the last four years and saved our plum crop each year. We also sprayed each year and had a very good crop of plums when neighbors who had not sprayed had very few, and I am satisfied if we use the proper ingredients and spray properly at the right time, and occasionally use an orchard heater when there is any danger of freezing, that we will raise a good crop of most any plum that is hardy enough for this climate.