Part 15

"Mr. Cook, what is the use of making all of this fuss about these new plums? Plums are only used for the purposes of making jelly anyway, and we can usually get a dollar a bushel for our plums, and they would not pay any more than that, no matter how large and fine they are."

This brought me up with a jerk, and I have concluded that no matter how advanced a place in horticulture these new hybrid plums may eventually take, that there will always be a place for our native varieties, even if only for the purpose of making jelly.

It seems to the writer that in view of the fact that after many years' attempt to improve our native plum through the process of seed selection--and we have made no material advancement in that line--that the varieties of plums that are on the way must almost of necessity be the product of the Americana and some of the foreign varieties of plums.

Mr. Theo. Williams, of Nebraska, a few years ago originated a great many varieties of these hybrid plums. He claimed to have upward of 5,000 of them growing at one time. Only a few of them, however, were ever sent out. Of these the writer has been growing for quite a number of years the Eureka, Emerald, Stella, Omaha, B.A.Q. and some others. As a class they are all reasonably hardy for my section. They grow rapidly, bear early, usually the season after they are planted or the top grafts set. They set fruit more freely and with greater regularity, as the seasons come, than do the best of our native varieties. The fruit is of larger size and of firmer flesh, while the quality of some of them, like the B.A.Q., ranks rather low. The quality of others of them, like the Emerald, is almost beyond comparison.

One year ago in answer to a question by the writer as to why the people of Iowa did not take more interest in the planting of these hybrid plums of Mr. Williams, Mr. C.G. Patten stated that it was because the plums rotted so badly on the trees. Now, Mr. Patten stated the situation exactly--most of these fine varieties are notoriously bad rotters. The brown rot seems to be a disease of moist climate. Nature's remedy is an abundance of sunshine and a dry atmosphere, but we cannot regulate the climate. Prof. Hansen has sent out a few varieties of these Japanese Americana hybrid plums, and our Supt. Haralson is doing a great work along this line. We can only hope--but cannot expect--that Mr. Hansen's hybrids or Mr. Haralson's hybrids as a class will prove more resistant to the brown rot than do those of Mr. Williams of the same class.

We have hopes that from some of Mr. C.G. Patten's hybrids of the Americana and Domestica plum will come some varieties worthy of general planting, and also of Prof. Hansen's crosses of the Americana plum and the Chinese apricots.

There is another class of hybrid plums that are something wonderful in their way, beginning to bear nearly as soon as they are planted, the very earliest of all plums to ripen its fruit, immensely productive and of finest quality. I refer to Prof. Hansen's sand cherry hybrid plums. My opinion is that Prof. Hansen has done all that man can do in the way of producing elegant varieties of this class of fruit. But there is the uncertainty, however, or perhaps I had better say the certainty, that the brown rot will take a good portion of the crop nearly every season--sometimes only a part of the crop, and other seasons it may take the entire crop of these fine sand cherry hybrid plums.

Bordeaux mixture has been the one remedy advertised for years for the control of this disease, and however well it may work in the hands of experts of the various university farms, it has not proved uniformly successful in the hands of the ordinary fruit grower.

Now, if some medicine should be invented, or some magic made, whereby the brown rot would be banished from our orchards then a great many of the fine varieties of hybrid plums would be transferred from the "plums that are on the way" to the list of "plums that we already have." The brown rot is a controlling factor.

Mr. Kellogg: What do you know about the Surprise?

Mr. Cook: Oh, I know a little more than I want to know about it. I have had the Surprise a good many years.

Mr. Kellogg: You have been surprised with it?

Mr. Cook: Yes, sir, I have been surprised quite a bit, but in the last two years since the plum crop failed there have been a few plums on the Surprise trees, but for a great many years when other plums bore heavily we got nothing.

Mr. Hansen: Do you know of any plum that has never had brown rot?

Mr. Cook: In my paper--as they only allowed me fifteen minutes I had to cut it short, and I didn't say very much about the brown rot. All the Americana plums, and all varieties of plums I have ever grown, have in some way been susceptible to the brown rot, but some have been more resistant than others. Now, that is one reason, I believe, why the DeSoto takes the lead. It is less subject to the brown rot. We have here a moist climate, and sunshine and dry atmosphere is the remedy, but some of these varieties have such a peculiar skin it is resistant to brown rot, and it seems certain, I don't know, if it is not on account of the thick skin. The Wolf has a thick skin and is subject to brown rot, but the DeSoto is not subject to that so much but more subject to the curculio. The Japanese hybrid plums, Mr. Williams said at one time--I saw in one of the reports--that he had Japanese plums enough to grow fifty bushels of plums, but he generally only got a grape basket full. He didn't think very much of them. In these sand cherry hybrids, I think Mr. Hansen has done all that man could do.

Mr. Ludlow: What is the difference between the brown rot and the plum pocket fungus?

Mr. Cook: Professor Stakman will tell you that in a later paper, but it is an entirely different disease. The brown rot will work the season through. It will commence on some varieties and work on the small plums and work on the plums half-grown and on the full-grown. The plum pocket fungus, it works on the plums in the spring of the year and sometimes takes the whole crop. The Terry plum, I think, a year ago, it took the whole crop.

Mr. Kellogg: What is the best spray you know of, how often do you apply it and when?

Mr. Cook: Which is that for, for the brown rot?

Mr. Kellogg: Yes, for the plum generally.

Mr. Cook: Oh, I don't know of any. Let me tell you something, the plum as a class is very susceptible to injury from sprays. I know when Professor Luger was entomologist there was some talk of spraying plums for curculio, and some tried it, and while it generally got the curculio it killed the trees, and Professor Luger said that the foliage of the plum was the more susceptible to injury from arsenical poisoning than that of any other fruit in Minnesota. The Japanese hybrid plums, I think, will take injury a little bit quicker than the native, and when you come to the sand cherry plums it is extremely dangerous to spray with anything stronger than rain water.

Prof. Hansen: I want to talk about the lime-sulphur. We will probably have that in the next paper, only I want to say that seems to have taken the place of the Bordeaux mixture. Brown rot, that is something that affects the peach men too. In the state of Ohio in one year the peach men lost a quarter of a million dollars from the brown rot, the same rot that takes our plums. We are not the only ones that suffer from the brown rot. Well, they kept on raising peaches because they learned to control it, and if you are not going to spray I think you better give up. As to trying to get something that won't take the rot, it is something like getting a dog that won't take the fleas. (Laughter.)

Mr. Older: I had considerable experience in putting out seedling plums. When large enough to get to bearing there wasn't a good one in the whole lot. I got some plums, the finest I could pick out, and three years ago they first came into bearing, and one of my neighbors went over there when they were ripe and said they were the best plums he had seen, but since then I have had none. I got some Emerald plums from Mr. Cook. They were nice plums, and when he came to see them he said, "I came to see plums, I didn't come to see apples," but the brown rot gets a good many of them. I had some last year, and just before they ripened the brown rot struck them, and it not only took all the fruit but got the small branches as well. I don't know what to do about the brown rot.

Mr. Drum: I would say that my experience was something like Mr. Older's with the sand cherry crosses. They grew until they were large and I sprayed them with lime-sulphur. I couldn't see any injury from that until they were grown, nearly ripe, and then in spite of me in a single day they would turn and would mummy on the trees. I had a Hanska and Opata and the other crosses, and they bore well. They were right close to them, and the brown rot didn't affect them particularly.

Mr. Ludlow: I would like to ask these experts what is the life of a plum tree. Now, an apple tree, we have them that have been bearing for forty years, but my plum trees that were put out less than twenty years ago, they got to be a thicket and they don't bear any large plums at all. I introduced years ago, if you remember, the Ocheeda plum, that come from seedlings that we found in the wild plum at Ocheeda Lake. It is a very fine plum. I had about twelve bushels this year, and I have never seen a bit of brown rot in that variety of plums, although the other varieties, if they bore at all, they were brown rotted all over. The Ocheeda plum has a very thin skin, and when the rain comes at the right time and the sun comes out they all split open. That is its fault. But my orchard is getting old; it is twenty years old. I had a young man work for me, and he left me and bought a new place. I told him he could take up all the sprouts he wanted of those Ocheeda plums. He did so and put out an orchard of them. I think that was about ten years ago. This year while my plums didn't average me, my Ocheedas didn't average, over an inch or an inch and an eighth in diameter from that old orchard--he had sold out and gone to California--but from that orchard a man that never thinks of cultivating sold three wagon loads of the finest plums I ever saw.

Mr. Kellogg: How large were the wagons? (Laughter.)

Mr. Ludlow: Well, the ordinary wagon box. He hauled them and sold them in town. That was from an orchard that had been left without any cultivation.

Mr. Philips: I have heard George Kellogg say you could prove anything in the world in a horticultural meeting. I was glad to have Mr. Cook say a word in favor of the DeSoto. The first plum I ever bought was a DeSoto thirty-five years ago. I planted it and never saw any brown rot on it and had five bushels on it this year. George Kellogg saw it; I can prove anything by him. (Laughter.) Talking about Prof. Hansen's sand cherry crosses, I have a number of his trees. I have two in particular that are nice trees. My wife the last three years has selected her plums from these trees for preserving and canning. I never saw any brown rot on them. They are nice trees, and I propose to stick by Hansen as long as he furnishes as good stuff as that. The locality makes a great difference in this brown rot. Some of the smaller varieties of Prof. Hansen the brown rot takes. As some one has said, it will take the plums and the twigs after the plums are gone. It may be that the locality has something to do with it.

Mr. Cook: A year ago I was talking with some gentlemen in the lobby of this hotel here and among them was a gentleman from the Iowa society, and I was trying to urge and tell them about the great value of some of those hybrid plums. Mr. Reeves said to me: "Mr. Cook, if you were going out into the woods to live and could only take one variety of plum with you, what variety would you take?" If he said five or six different varieties I would have made a different answer but he said only one variety, and I said it would be the DeSoto, and his answer was, "So would any other man that has right senses about him."

Mr. Anderson: It was my pleasure some time ago, I think it was in 1896, to set out a few plum trees, DeSotos, and those trees grew and grew until they bore plums, and I was very much pleased with them. It was also my fortune about that time to sell plums that another man had grown, such varieties as the Ocheeda, the Wolf and the Wyant. They were such beautiful plums, and I obtained such beautiful prices for them, I was very much enthused over growing plums. I purchased a number of trees of that variety, but up to the present time I have never marketed a bushel of plums from any tree of that kind. The DeSotos bore plums until they died a natural death, which was last year.

Mr. Goudy: I have one DeSoto in my orchard which is seven years old, never had a plum on it, never had a blossom on it. What shall I do? (Laughter.)

Mr. Ludlow: Cut it out.

Spraying Plums for Brown Rot.

PROF. E. C. STAKMAN, MINN. EXP. STATION, UNIVERSITY FARM, ST. PAUL.

The brown rot of plum is without doubt one of the important limiting factors in plum-growing in Minnesota. In seasons favorable to its development, losses of from twenty to fifty per cent. of the crop in individual orchards are not uncommon.

Experiments on the control of the disease have been carried on by the sections of "Plant Pathology and Tree Insects and Spraying," of the Minnesota Experiment Station, since 1911. No accurate results could be obtained in 1912 and 1915 on account of crop failure in the orchards selected for experiment. Results are available for the years 1911, 1913 and 1914.

Brown rot is caused by a fungus (_Sclerotinia cinerea (Bon.) Wor._). Every plum grower knows the signs of the disease on the fruit. Blossoms, leaves and twigs may also be affected. The diseased blossoms become brown and dry, and fall from the tree; the diseased leaves become brown and may die. Young twigs may also be killed.

Infection may occur at blossoming-time. The amount of blossom blight depends very largely on weather conditions; in fairly warm, moist weather there is usually more than in drier weather. The same is true of the rot on the fruit; during periods of muggy weather it may spread with amazing rapidity. The rot does not usually attack the fruit until it is nearly or quite ripe, although green plums may rot, especially if they have been injured. It is important to know that a large percentage of rotted plums have been injured by curculio. Counts have shown that in many cases as much as eighty-five per cent. of the rot followed such injury.

Rotted plums should be destroyed for two reasons: (1) The spores produced on them may live during the winter and cause infection in the spring; (2) if the mummies fall to the ground, late in April or early in May of the second spring the cup fungus stage may develop on them. This cup fungus produces a crop of spores capable of causing infection.

Spraying experiments, the summarized results of which are given here, show that the disease can be fairly well controlled even in badly affected orchards.

Some of the experiments were carried on in the orchards at University Farm and some in commercial orchards. There were from twelve to forty-five trees in each plot, and the trees on which counts were to be made were selected before the rot appeared. The percentages given below refer to fruit rot and do not include blossom or twig blight. The object was to determine the times for spraying and the most effective spray mixtures. Details are for the most part omitted, and the results of various experiments are averaged.

For convenience the times of spraying are designated as follows:

1. When buds are still dormant. 2. When blossom buds begin to show pink. 3. When fruit is size of a pea. 4. Two weeks after third spraying. 5. When fruit begins to color.

It did not pay to apply Spray 1. In the plots on which applications 1, 2, 3 and 4 were made there was an average of 6.3 per cent. of rot, while in those from which Spray 1 was omitted there was an average of 6.7 per cent. rot, a difference so slight as to be negligible. Neither did Spray 4 seem to pay, there being an average of 10.9 per cent. brown rot when it was applied and 11.4 per cent. when it was omitted.

The schedule finally adopted was therefore the application of Sprays 2, 3, and 5. Spray 2 is necessary to prevent blossom blight, although it has not always reduced the amount of rot on the fruit. Spray 5 is the most important in reducing the amount of rot. In all of the experiments during three years the average amount of rot in the sprayed plots which did not receive Spray 5, was 10.7 per cent. On the plots which received Spray 5, with or without the other sprays, the average amount of rot was 4.6 per cent., and the average on unsprayed plots was 34.8 per cent. Excellent results were sometimes obtained by applying only Spray 5, although this did not, of course, have any effect on blossom blight. In 1913 the amount of brown rot in one plot which received only Spray 5 was 3.3 per cent., while in the unsprayed plots it was 33.9 per cent. In 1914 the amount of rot was reduced from 38.8 per cent. in unsprayed plots to 6.5 per cent. in the plots to which Spray 5 was applied. Possibly Spray 3 could be omitted without seriously interfering with results; success in controlling the rot with Spray 5 alone seems to indicate this. It was hoped to settle the matter during the past summer, but spring frosts spoiled the experiment.

For the present it seems advisable to recommend the application of Sprays 2, 3, and 5. In the first two, two and a half pounds of arsenate of lead paste, or one and one-fourth pounds of the powder should be added to each fifty gallons of spray mixture in order to kill the curculio. In the plots sprayed in this way in 1911 ninety-six per cent. of the fruit was perfect, while in the unsprayed plots only 81.6 per cent. was perfect, and in 1913 and 1914 the amount of brown rot was reduced from 34.8 per cent. to 4.6 per cent. Several growers have reported excellent results from these three applications, and there is no reason why other growers should not duplicate them.

The efficiency of various fungicides was tried. Self-boiled lime-sulphur, 8-8-50; commercial lime-sulphur, 1 to 40; 2-4-50 and 3-4-50 Bordeaux; iron sulphide made up with 1 to 40 commercial lime-sulphur, and iron sulphide made up with 10-10-50 self-boiled lime-sulphur were tried and all gave good results. Commercial lime-sulphur, 1 to 40, has been used in commercial orchards with excellent results, and it will probably be used more than the other spray mixtures because it is so easy to use. Possibly weaker solutions of lime-sulphur would do just as well as 1 to 40. This will be determined, if possible, during the summer of 1916.

Good results were obtained only when a high pressure was maintained in spraying. There was a clearly observable difference between plots sprayed with low pressure and those sprayed with a pressure of more than 175 pounds. For large orchards a power sprayer is desirable; for small orchards a barrel sprayer with an air-pressure tank attached is large enough. Such an outfit can be bought for $35 or $40 and can do good work.

The cost of spraying three times should not exceed fifteen cents a tree. The results from spraying orchards which contain a great deal of brown rot and have never before been sprayed will probably not be so good the first year as in better kept orchards, but by spraying regularly each season the disease can be well controlled.

Mr. Cashman: Please state what you mean by 3-4-50 there.

Mr. Stakman: 3-4-50 Bordeaux mixture means three pounds of bluestone or copper sulphate, four pounds of lime, and fifty gallons of water. The copper sulphate should be dissolved in twenty-five gallons of water, the best way being to put it into a sack and hang the sack in the water. The lime should be slaked and then enough water added to make twenty-five gallons of milk of lime. Here is where the important part of making up the spray comes in. Two people should work together and pour the milk of lime and the bluestone solution together so that the streams mix in pouring. It is very important that the mixing be thorough and the mixture should be used fresh.

The President: Do you add any Paris green at any time or arsenate of lead?

Mr. Stakman: Always add arsenate of lead two times, when the buds are swelling and when the plums are the size of green peas.

The President: How much?

Mr. Stakman: I would rather leave that to Professor Ruggles. We used from 2-1/2 to 3 pounds and Mr. Ruggles, I think, found 2-1/2 pounds was enough.

The President: That is, 2-1/2 pounds to 50 gallons of water with the other ingredients?

Mr. Stakman: Yes.

Mr. Dyer: I would like to ask if you have ever used arsenate of lead for spraying plums?

Mr. Stakman: In the experiments which we conducted in co-operation with Mr. Ruggles, of the Division of Entomology, we always used arsenate of lead in the first two sprayings to kill the curculio.

Mr. Dyer: I had quite an experience, so I want to know what your experience was.

Mr. Stakman: We never had any trouble with it.

Mr. Dyer: I have had an experience of thirty years, and I have never seen or had on my place any brown rot, and I never was troubled with any curculio, and I practically always used arsenate of lead.

Mr. Cashman: Isn't it a fact if you begin spraying your plum trees when they are young and spray them early, at the right time, you have very little trouble with the brown rot? And spray them every year?

Mr. Stakman: Yes, that is it. You might be disappointed the first year if the orchard had never been sprayed, but by spraying year after year you finally cut it down.

Mr. Cashman: You said a pressure of 200 pounds ought to be used?

Mr. Stakman: Yes, but it isn't necessary to get an expensive power sprayer to keep up that pressure. There are sprayers on the market that cost from $30 to $40 which have a pressure tank by which the pressure can be maintained at from 175 to 250 pounds without any great amount of trouble, that is, for a small orchard. If you have a big enough orchard for a power sprayer, of course get it.

Mr. M'Clelland: This summer my plum trees, the leaves all turned brown and came off. What is the reason?

Mr. Stakman: When did it happen?

Mr. M'Clelland: Along in August, I think; July or August.

Mr. Stakman: What kind of soil were they on?

Mr. M'Clelland: Clay.

Mr. Stakman: Did you spray?

Mr. M'Clelland: Yes, sir, I sprayed.

Mr. Stakman: What did you use?

Mr. M'Clelland: Lime-sulphur, I think.

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 arsenate of lead.