During the last two years I have been working along a line which is entirely different from the treatment of the maggot, and that is based upon the fact that the fly which lays the egg which produces the maggot in the cabbage comes out early in the spring and flies about the field for probably a week or ten days or two weeks before it lays its eggs, and during that period it eats any sweet material which happens to be on hand. With this as a basis we thought we might be able to poison the flies and thus prevent injury from the maggots, and we have tried several different spray mixtures along that line. One mixture which we use is a mixture which is normally used against the fruit flies which are oftentimes injurious to fruit, particularly in the east and in tropical countries. This contains three ounces of arsenate of lead, two and half pounds of brown sugar and four gallons of water. The idea is to spray this in the field, spraying it on the plants as soon as the plants are put out in the field. We have more or less definite dates for the appearance of the flies in the field and for their disappearance again. But, as you know, the season varies, and the result is somewhat uncertain. So probably the best method is to base it upon the time you plant out your cabbage. In the early seasons you will plant your cabbages early, and in the late seasons later. So plant out your cabbage and then spray them every week until the 10th of May.
You should spray them, not to cover the leaves with the poison, but merely sufficient so that there are a few drops of this poisoned material on the leaves so that the flies can eat it. Flies will come there and feed upon this mixture and die.
It is rather peculiar that we started work here about the same time on the cabbage maggot that they started work on the onion maggot along similar lines in Wisconsin. I don't think that either knew that the other was working towards that end. They used a different mixture, one-fifth ounce of sodium arsenite, one-half pint of New Orleans molasses and one gallon of water. This was sprayed over the onions and was very successful in controlling the onion maggot.
I tried their mixture this last year. They published some of their results last year, so it gave me an opportunity to watch their mixture in comparison with the lead arsenate. They claimed the lead arsenate did not act as quickly as the sodium arsenite. That is true, but when you have a ten-day period to kill the fly it don't make much difference whether it dies in ten hours or twenty-four. The flies are not doing any injury. If you take the lead arsenate and sugar and water and put it in a jar, the arsenate always sinks to the bottom, and if you were to test it that way, the fly would feed on the top and you might not get a quick result. But if you spray it on, the lead arsenate will kill as quickly as the sodium arsenite.
There is an objection to the use of arsenite in that sodium arsenite is a soluble poison and will burn the leaves of the cabbage. Of course, that is not particularly serious as those are the first leaves the cabbages have and the cabbage soon gets over any slight injury, but many truck gardeners probably would object to that. In the onion you have a different shaped leaf, and the injury is not so apparent. Last summer I found that New Orleans molasses would give you a little bit better result than the sugar, and it is cheaper. The objection to the New Orleans molasses is the sticky nature of the material in handling.
I might mention in regard to opening cans of New Orleans molasses. If you never opened one and try this treatment, be careful about opening the can. The lid is pushed down tight and under warm conditions, or if the molasses has been in a warm room there is a certain amount of fermentation and gas under pressure, and if you pry it open quickly you find the lid flies up in the air and you will probably be smeared over with molasses.
I employed my spray, that is, one ounce of lead arsenate, one-half pint of New Orleans molasses and one gallon of water last season. The check plots had cabbages attacked by the maggots, probably 10 or 15 per cent of the plants dying from the attack. Last year was a very good season, that is, many of the plants seriously attacked put out roots again, and those were able to grow again in the sprayed plots. The infestation of the sprayed plots was probably about 30 to 40 per cent. of the plants, but they only contained probably one maggot each, which is very slight and not sufficient to do any damage.
There is one market gardener whose cabbage patch we sprayed, I think, only a part of two rows, and we thought we would leave the rest of his patch as a control. Apparently the amount of material we put on there was sufficient to attract the flies from the whole field. Not a single cabbage died, and he was pleased with the result of the spray.
Mr. Miller: What do you do for root aphis?
Mr. Moore: Root aphis can very easily be controlled with tobacco extract. It is put upon the root of any plant that is affected, a tablespoonful to a gallon of water. There are a number of different tobacco extracts on the market. Some of them contain 15 per cent. of nicotine, some contain 20, some 25 and some 40, and I think there is one brand that contains 45 per cent. You will find that the brands that contain the most nicotine are the most expensive, but in proportion you use less material. Thus 20 per cent. tobacco extract would take two tablespoonfuls to the gallon, while 40 per cent. would take only one. It is the nicotine which is the working portion of it.