necessary to make the application of a fungicide before the blossoms open but after they show pink. The second application should come at the same time as that for codling moth, and should serve to prevent infection to the recently developed leaves and fruit. The third application should come about two or three weeks later, depending upon the weather. Entomologists are recommending an application about three weeks after the petals fall. Those three applications are generally recommended for apple scab. It may not be necessary to make them all. One spraying has controlled apple scab, but it is no guarantee that you will not have it. If weather conditions are favorable for scab in late summer it may develop then, especially if it has been abundant earlier. An application of a fungicide in the latter part of July will do much to hold such a late infection in check. QUESTION: Would dormant spraying do any good? PROFESSOR BARRUS: No sir; not for apple scab. QUESTION: Do you make a dormant spray late enough so you can catch the apple scab the first time? PROFESSOR BARRUS: No, not as a usual thing. QUESTION: Wouldn't the spores develop on the branches? PROFESSOR BARRUS: No; only in exceptional cases. There are a few varieties where they occur on the branches. They do occur in the case of pear scab, but not usually in apple scab. EIGHTH SESSION WEDNESDAY, MARCH 17, 1:30 P. M. ROUND TABLE MR. VAN WAGENEN: For the next half hour we will have the Round Table, or open discussion. I have two questions here which I will simply turn over to Professor Parrott. PROFESSOR PARROTT: These two questions deal with spraying. The first is, What can be done to stop the injury of the quince curculio? The curculio which attacks this particular fruit was very injurious this past year. Unfortunately, it is not a pest that can be held by the same measures, with satisfactory results, as are used with the plum curculio. It cannot be destroyed entirely by the use of arsenical sprays. The first thing is cultivation of the quince orchards, and then the jarring of the trees and destroying of the beetles as they fall to the ground; then thinning of the quinces, taking off fruit most affected and destroying the fruit when the grubs are still in them. Then, of course, it would pay to follow the ordinary schedule that is followed in a pear orchard to fight the common insects. The second question is, Can the commercial hydrated lime, be used in making lime-sulphur; if so, to any advantage? There is no advantage in doing so, and as a matter of fact, I think there is a possibility of a great disadvantage; that is, the presence of air-slaked lime in the material. I would advise you to get the quicklime, purchasing that which tests high in calcium. QUESTION: What about whale-oil soap and crude carbolic acid to kill aphis? PROFESSOR PARROTT: The proper name for this spray, by the way, is crude carbolic acid emulsion." It is not a new spray; it has been known for a great many years, and was originally introduced about 1880, by Professor Cook of the Michigan Agricultural College, to destroy the root maggot. As to its merits, I believe that, taking it for itself, it will prove an admirable spray for plant lice. I would class it with those other sprays used in spraying for aphides, and would say that you will get satisfactory results with any of those mixtures. Unfortunately, crude carbolic acid cannot be combined with any of our common orchard insecticides, such as lime-sulphur solution; so you will need to use it separately in spraying for lice, unless you are using certain oil emulsions. I would say that it is somewhat cheaper. Here are some figures that will be of interest to you, based on applying these different preparations to twelve old trees. By using the formula of 15 pounds soap, at 5 cents a pound, and one pint of crude carbolic acid at the rate of 50 cents a gallon, the cost of application will be about $1.51 for the twelve trees. If you apply Black-leaf-40 and soap, at the usual application, it would cost you $1.85, as against $1.51 with the crude carbolic acid emulsion. But the advantage with nicotine, of course, is that you can combine it with lime-sulphur and thus save the cost of labor of a second treatment. VOICE: I know of some that tried the nicotine this year, and they said they tried to be thorough about it, but they were not sure that they obtained any results. PROFESSOR PARROTT: Yes; that will be true under almost any circumstances, especially if the leaves are actually curled, in the case of lice. But if you apply either the crude carbolic acid emulsion, or nicotine and soap, or kerosene emulsion, at the proper time, I think you will find they will not differ. QUESTION: Is this crude carbolic acid and whale-oil soap effectual for red bug? PROFESSOR PARROTT: We have never made a test for it. I am of the opinion that nicotine has one peculiar merit not possessed by most of our more common insecticides; namely, its ability to kill after application. MR. BOGUE: If arsenate of lead, by mixing with lime and sulphur, will harden on the tree, why not use plain arsenic and lime, which will remain on the tree for three months and always be pliable and soft for the worms to work on? PROFESSOR PARROTT: Well, I imagine that is a thing to be worked out; I could not tell. The one objection to using white arsenic is that a goodly percentage of it may be soluble in water, and if the arsenic is applied by itself you will have burned foliage. The object in adding lime to white arsenic is to neutralize the free arsenic. But it is a preparation which has gone out of use, because arsenate of lead is better than it; I mean so far as killing the worms is concerned. I cannot see why it could not be added, except that you would get more free arsenic. MR. BOGUE: When you put the arsenate of lead on a tree it hardens after three or four days. The question is, When worms work on that tree are they going to work in the hard or the soft application? Last year we had a great many worms on our apples. I applied the arsenic and lime last September, and it is on there today, where it can be seen. I examined it a great many times and found it soft. PROFESSOR PARROTT: You cannot see the combination with the lime-sulphur. There is a reason why we use the lead arsenate. The great reason is that it is the safest to use with limesulphur. Then it possesses adhesiveness. A man could get this combination and get fair results, I imagine. MR. BOGUE: Couldn't that be put on afterwards and still get the results? PROFESSOR PARROTT: There is the question again of making the extra application. The practical experience with arsenate of lead in most orchards is satisfactory. MR. VAN WAGENEN: effect on vegetable life? Does carbolic acid have an unfavorable PROFESSOR PARROTT: There is no question about that. But I do not think that people in this community are going to rush to new and untried sprays at the expense of precaution. Carbolic acid is a very toxic substance, both to insects and plant life, and if you use it on foliage you must be careful to get a perfect emulsion and not drench the trees too much. We are now working on a formula with Mr. Lasher, in order to find out how greatly we can reduce the amount of carbolic acid in the preparation and still have an efficient spray. PROFESSOR HEDRICK: I have another question here: If color is to make an "A" grade apple, will it pay to prune very heavily and drift back to sod culture? |