Wisconsin State Cranberry Growers Association / Wisconsin State Cranberry Growers' Association. Forty-seventh annual meeting, Wisconsin Rapids, Wisconsin, December 14, 1933. Forty-seventh summer convention, Wisconsin Rapids, Wisconsin, August 8, 1933
Goldsworthy, Vernon C.
1933 insect situation in Wisconsin and control methods, pp. 33-39 PDF (1.7 MB)
34 WISCONSIN CRANBERRY GROWERS' ASSOCIATION for its control has ever been worked out. Sanding, destruction of wild fruit surrounding the marsh in which they breed, putting water on early in the fall for two weeks when the water is warm (60' F) all help some, but none of these methods give very good control. Trichagamma parasites were tried the last two years and while they seemed to be of a benefit, I found they did not give as good a control as hoped for, although it is extremely difficult to check closely. The cranberry leaf-miner (Coptodisca negligence) which is strictly a Wisconsin cranberry insect and has never been reported on any other cranberry marsh, except in Wisconsin, is increasing particularly on the northern marshes. Excellent method of control has been worked out by the author which consists of a nicotine sulfate spray applied shortly after the moths emerge and before they have a chance to lay eggs for the next year's brood of leaf-miners. Usually three sprays must be applied at intervals of three or four days as the moths do not all emerge at the same time. The adult moth appears about July 4th. There is one brood a year. The leaf-hopper population on Wisconsin marshes is increasing and false blossom is spreading. Do not think for one minute because you cannot note its spread readily with the naked eye that it is not spread- ing. False blossom is an insidious thing and is spreading unquestion- ably on every marsh in the state to some extent and will continue to spread as long as the blunt-nosed leap-hopper (Euseelis striatulus) is present and diseased vines are available as a source of the virus. Some marshes do not have many of the blunt-nosed leaf-hoppers, the only carriers of the disease, but on any marshes where the hoppers are pres- ent in any numbers they must be fought at once. Do not wait until there is a fair percentage of false blossom in a section, or leaf-hoppers three hundred to four hundred in a hundred sweeps-it is too late then for control, just like locking the stable after the horse is stolen. When 50% of the vines become infected it is merely a question of time when the balance will become worthless, unless, of course, dras- tic conditions alter its spread. Moreover, remember false blossom vines, once they become badly diseased, do not bear fruit and never recover. Just stop and think-suppose a section is 50%e false, you are only getting one-half a crop, and you will never get any more, but less and less. Suppose you have a section of good Searls Jumbo and they yield 100 barrels to the acre. If the section becomes 50% in- fected, you lose fifty barrels and even at the low price of $8.00 per barrel that means you are losing $400 an acre, and on a marsh of twenty acres that would mean $10,000 a year. Do not trust your eye to tell you if the disease is increasing-there is no man on earth, no matter who he is, that can positively tell the current year's infection and the only way an infection can be detected is by waiting at least one year and seeing the symptoms which we are all so familiar with, and when we see the symptoms the vine is hopelessly lost. Once again, let me caution you not to wait before practicing control if you have the leaf-hoppers in any quantity. Vines vary in their susceptibility to false blossom. but no vines or variety are immune. McFarlin vines are quite resistant, but in the author's thesis an experiment reported and conducted under the di- rection of Mr. Bain and suggested by him proved verv conclusively that the McFarlin will take the disease when exposed to the feeding of hoppers which have been infected by first feeding on diseased vines. Dr. Franklin in the East has proven the disease is insect borne, and a repetition of his experiments in Wisconsin bv Bain, Rogers and Golds- worthy uphold this fact. Some growers still believe that cultural con- ditions cause false blossom, such as dryness or wetness. I will def- initely state that I will give any cranberry plant that anyone in the world may pick out the disease of false blossom absolutely every time
This material may be protected by copyright law (e.g., Title 17, US Code).| For information on re-use, see http://digital.library.wisc.edu/1711.dl/Copyright