The varieties used were Long Green cucumbers and Hubbard squashes. On April 24, strawberry boxes were used to plant the seeds. Twenty-five boxes were planted with cucumber seeds, using ten seeds in each box. Also twenty-five boxes of squash seed were planted using six in each. These were put in a greenhouse. On the 12th of May, out of 150 squash seeds planted, only 40 squash plants lived and 38 cucumber plants out of 250 seeds planted. Consequently it was necessary to replant these boxes with seeds. On May 24th and 25th one row each of cucumber and squash plants were set in the field from those started in the greenhouses and protectors placed over them like those shown on plate IV, c. The rest of the field was planted with seeds. The cucumber plants were all badly sunburned and consequently were replanted on May 31st. On June 14th and 15th the above-mentioned treatments were applied to the remaining plants, which were few. It was necessary, therefore, to plant over nearly all squash and cucumbers on June 16th. On July 3d, in order to have a good stand several more seeds were planted in the squash plot, none, however, were planted in the cucumber plot. The protectors that were used on the cucumbers and squash were removed on this date, the plants filling the space under them. Another application of remedies was made on July 5th, this being the last treatment given to the cucumbers. METHODS OF CONTROL. Under ordinary conditions a great majority of these beetles can be controlled by spraying or dusting with arsenical poisong but when they are abundant it is a difficult matter. It is, therefore, necessary to use more than one method in order to satisfactorily control this pest. Cultural methods, repellents, preventatives, and insecticidal methods are commonly practiced, collectively, to obtain the best results. CULTURAL PRACTICES. Clean culture is an important factor in controlling this pest. When the crop has been harvested, all refuse, including all the old vines, should be removed from the field and burned. This will destroy a great many of the beetles that would otherwise hibernate, and therefore lessen the number of beetles to attack the plants the following spring. Plowing. After the crop has been harvested and all refuse removed, harrowing the ground lightly will kill many adults that remain near the surface before hibernating. Plowing deeply in the spring will also kill many hibernating adults. Trap crops. Beans and squashes have often been planted as trap crops, especially by market gardeners who grow quantities of melons. Young squash plants are a favorite food of these beetles and are preferred by them to the cucumber. If squashes are planted in the spring, a week or ten days before the cucumbers or melons, the beetles will feed on them before the cucumbers push out of the ground. Then poison the squashes with arsenate of lead. Squashes or beans can also be planted around the borders of the field late in the season in order that the new generation of beetles can have tender food on which to feed. Those of the new generation feed before hibernating and if this food is provided, just as soon as they begin feeding upon it the young plants can be sprayed or dusted with an arsenical poison. This will kill many of the beetles before they seek winter quarters. Rotation of Crops. A field that has been infested by these beetles should not be planted with cucurbits for at least two years, neither on nor near the previously infested ground. Rotation of crops for two, and better, three years, will lessen the infestation. Fertilizers. The use of quick-acting fertilizers will enable the plants to make a quick growth. This will help them, to some extent, to outgrow the attack of the beetles. Time of planting, etc. It is advisable in the early spring to start the plants in a greenhouse or in frames. If this is done early enough so that the plants are of a fair size when set out in the field, they will be able to withstand the attack of the beetles. If this cannot be conveniently done, it is well to plant nearly twice as many seeds to a hill as are necessary. Later, if more plants survive the attack than are needed, it is an easy matter to thin out to the desired number. Some vegetable growers recommend several plantings to be made a few days apart. This will undoubtedly prove more or less satisfactory, but it has the tendency to produce a late crop. In Connecticut, at least, it is important to produce cucumbers just as early as possible, before the market has been flooded. PROTECTIVE METHODS. Protectors. For many years coverings of some sort have been used as a protection for the young plants against the adult beetles. There are many different kinds of coverings on the market and many home-made devices are used. In 1916 protectors were purchased from Joseph Breck & Sons, Boston, Mass., to be used in connection with our field tests. At that time the price was $1.50 per dozen. These protectors have been used for two seasons and are shown on plate IV, c. A majority of these can be used at least another season without many repairs. Serviceable protectors can be made at home by cutting a barrel hoop in two, crossing the halves, and tacking the ends to another hoop. This frame is then covered with mosquito netting like those purchased. The protectors have proved satisfactory, although if the cloth becomes broken the beetles can crawl through. Wire screening is more substantial but more expensive. If the frames are covered with wire screening they can be used from year to year. REPELLENTS. Tobacco, Naphthalene. Many repellents have been used from time to time but without any particular results. Tobacco dust has been tried in Connecticut without great success, although it has the advantage of acting as a fertilizer. Naphthalene balls and flakes have been scattered around each hill without success. Fine Coal Ashes. Finely sifted coal ashes heavily dusted around the plants are more or less satisfactory in keeping the beetles away. Air-Slaked Lime. Dusting with air-slaked lime is an old time remedy and will prove successful when the beetles are not very abundant. Lime-Sulphur. Spraying with lime-sulphur has given better results than some of the above-mentioned materials. If used 1 to 50, it will not injure the foliage. Land Plaster or Gypsum. In using dry materials it is essential that the whole plant be thoroughly dusted. This is especially the case in using land plaster. If the leaves are merely covered with dust it will have the tendency to drive the beetles to the under sides of the leaves or to the stems of the plants. Where dry materials are used, the stems of many plants have been badly chewed near the surface, and sometimes beneath the surface of the ground. It is also true that even when the plants are covered with dust the beetles often feed on them. ARSENICAL POISONS. Arsenate of Lead. Arsenate of lead has been more successful in Connecticut than other artificial measures. This can be used either as a spray or dusted on the plants. When used as a spray, 3 pounds to 50 gallons of water is sufficient. Arsenate of lead can also be used in combination with other materials, such as Black Leaf 40 and lime-sulphur. Arsenate of Lime. This was applied in the form of a spray (1 oz. in 1 gallon of water) at the Station farm in 1917. As this poison injured the foliage where used at this strength, it cannot be recommended. CONTACT POISONS. Black Leaf 40. Black Leaf 40, a nicotine sulphate solution, has been used alone and in combination with lime-sulphur and arsenate of lead. Two teaspoonfuls of Black Leaf 40, one-half ounce of soap, and two ounces of arsenate of lead is the formula used. When used alone or with lime-sulphur, this material was not very effective, but the addition of lead arsenate increased its effectiveness. RESULTS. The following treatments proved effective in the order given in controlling the striped beetle in 1917. The materials used have been explained in previous pages and the results are based on the number of plants that remained after all applications had been completed. When beetles appear in great quantities, they cannot be satisfactorily controlled by simply one method. It is therefore necessary to use different methods in combination. Some of the principal methods which will give satisfactory results are the following: 2. Arsenate of lead, dry; spray alone or in combination. 3. Dusting, arsenate of lead, land plaster, air-slaked lime. 4. Lime-sulphur spray. 5. Planting an abundance of seed; then thinning. 6. Clean culture in fall. 7. Trap crops; squash and beans in spring and fall. Britton, W. E. & Lowry, Q. S. Rept. Conn. Agr. Expt. Station, pp. 116118, 1916. Chittenden, F. H. Bulletin No. 19, n. s. Div. Ent. U. S. Dept. Agr. pp. 48-51, 1899. Circular No. 31, Bur. Ent., U. S. Dept. Agr. 1909. Fitch, Asa. 10th Report of Noxious and Other Insects of the State of New York, pp. 443–440. Headlee, T. J. Journal of Economic Entomology, Vol. I, pp. 203-209, 1908. |