i ion * [7 v STATE PLANT BOARD April 1943 E-589 United States Department of Agriculture - - Agricultural Research Administration Bureau of Entomology and Plant Quarantine THE CONTROL OF THE TOMATO FRUITWORM, 2/THE TOMATO PINWORM, THE TOMATO RUSSET MITE, AUD HORNWORMS By Joseph Yfilcox and J. C. Elmore, Division of Truck Crop Insect Investigations Introduction Tomato plants and fruits are attacked commonly by several species of insects, and important among these are the tomato fruitworm, the tomato pin- worm, hornworms, and a new pest of tomatoes in California known as the tomato russet mite. It is the purpose of this circular to set forth methods of controlling these pests which have developed during recent years. The tomato fruitworm (Hel_iothi_s armg_era (Rbn . ) ) , also known as the corn earworm on corn and as the bollworm on cotton, is a pest of tomatoes, regu- larly or occasionally, in practically all sections of the United States where tomatoes are grown. Its principal damage to tomatoes is through the insects feeding on and in the tomato fruits, rendering them unmarketable. The tomato pinworm (Keiferia lycj^JP^J^ellj*- (Busck)) is a pest of tomatoes in southern California. It is known to occur in Arizona, New Mexico, Missouri, Florida, Mississippi. Virginia, Delaware, and Pennsylvania. In addition to tomatoes, this insect also occasionally attacks potato and egg- plant. In California, Arizona, New Mexico, and Florida' the tomato pinworm has been primarily a pest of f ield-grown tomatoes, whereas thus far in Missis-sippi, Virginia, Delaware, Pennsylvania, and Missouri it has been present only as a pest of tomatoes grown in greenhouses and in tomato fields near the infested greenhouses. The tomato russet mite (Phyllocoptes destructor Keifer) was first found in Modesto, Calif., in 1940. ~By 1941" "it" had spTead"" over most of the San Joaquin and Sacramento valleys and in 1942 it was widesproad in southern California. Besides tomato, other host plants recorded by the University of California aro petunia, nightshade, Datura, potato, and morning-glory. This mite is minute in size, and its presence on the plant can be detected only by a microscopic examination. However, the injury caused by its feeding is readily recognizable. The plants are first attacked at the base and the leaves develop a bronze appearance before they die. During warm weather the mites increase very rapidly and can kill a vine or a whole field in a few weeks if control measures are not applied promptly. l/ This supersedes Circular E-489"7"Suggestions for the Control of the Tomato Fruitworm, which was issued in September 1939. - 2 - There are two species of hornworms that attack tomatoes--the tomato horn- worm (Protoparce qu in quemac u 1 ata (Haw.)) and the tobacco hornworm (P. sexta ( Jo hanTJJ," which" are widely dis tribute d over this country. In certain sec- tions they are, unless controlled, very destructive. They feed on the foliage of the plant, first attacking the leaves, oftentimes stripping the plants to the point where only the main stalk or stems remain, (r Control ■•• The problem of controlling these several pests when they occur in the same field is somewhat involved, as a remedy for one may not be suitable for the other. In California the tomat* fields may be infested at some period during the same season with the tomato fruitworm, the tomato pinworm, horn- worms, the tomato russet mite, rutworms, and the beet armyworm. In consideration of these factors, the determination of the proper remedy or remedies will depend on the kind of insects present in the field.. The discussion on the control of these several pests and their joint control follows. Tomato Fruitworm Control Cryolite and calcium' arsenate- dusts arrd a bait prepared by mixing corn meal with cryolite are all about equal in effectiveness for the control of the fruitworm. The choice between these materials is discussed in more-detail in the following paragraphs, Cryo 1 jte . — Extensive experiments have demonstrated that this insecticide is one of the best and safest materials to use on tomatoes for the control of the fruitworm, and is superior in the control of the pinworm. The active ingredient in cryolite is sodium f luoaluminate. Tests with the several brands and with different strengths of cryolite have not shown any great degree of difference in control when they were used at the same sodium f luoaluminate content and at the same rate per acre. For example, the same control can be expected fmm the use of a total of 180 pounds per acre of cryolite dust con- taining 35 percent of sodium f luoaluminate as can be expected from the use of a total nf 90 pounds per acre of a cryolite dust containing 70 percent of sodium f luoaluminate. As it is cheaper to mix and apply 90 pounds of a dust containing 70 percent of sodium f luoaluminate per acre than it is to apply 180 pounds of the weaker dust, a 70-percent cryolite dust is . recommended for general use. Calcium arsenate. --Extensive experiments have demonstrated that calcium arsenate (undiluted-)- is as effective as a cryolite dust containing 70 percent of sodium f luoaluminate when both materials «.re used at the same rate per acre. Calcium arsenate also has the added advantage of being cheaper than cryolite and in being more effective than cryolite in the control of hornworms and the best armyworm. Calcium arsenate has the disadvantage when compared with cryolite of not being so effective in the control of the pinworm, and in humid climates it may seriously burn the foliage and fruit. Calcium arsenate is preferred for use in localities where there is no chance of a pinworm infestation and in localities where it can be used without burning the plants and fruit. < . - 3 - Corn meal bait. --This bait is prepared by mixing P pounds of corn meal (as finely ground, as for poultry, feed) with 1 pound of cryolite containing 90 percent of sodium fluoaluminate. A total of 180 pounds per acre of this mixture has proved to be about as effective in the control ef the fruitwcrm as a total of 90 pounds per acre, of a cryolite dust containing 70 percent cf sodium fluoaluminate, or as undiluted calcium arsenate. This corn meal bait mixture is cheaper than either.. . of' the .dusts and is scattered over the leaves of the plants by hand., no special equipment being necessary, but it has the disadvantage when compared with the dusts of being ineffective against the pinworm, hornworm, beet armyworm, and russet mite. When to treat* — The first application of either dust or bait for fruit- worm c^ntFoi™no'uTd be made as soon as the fruits »f the main crop begin to set. At this time, depending on weather and other growing conditions, the plants may vary from 1 to 3 feet in diameter but there will be an average of about 7 tomatoes per vine, 5 of which should be l/2 inch in diameter or less. Th<=> timing of the first application is very important, as under southern California conditions it has been demonstrated that a delay of 1 week in making the first application results in a marked increase in the number of fruits damaged by the fruitworm. Number of applications. — Three applications of either the bait or the dusts are made at 2-week intervals. Poundage of material per acre. --Experiments in southern California have shown that 90 pounds of the cryolite dust mixture containing 70 percent of sodium f luoaluminate, or of the undiluted calcium arsenate, is the most profitable quantity to use in this area. An application of a total of 150 pounds per acre for three applications proved superior to the 90-pound rate, but under the conditions of this experiment the added degree *f control did not justify the expense of the additional material. Under war conditions the 150-pound rate is justified in many fields. The experiments indicate that a cryolite dust mixture containing 70 per- cent of sodium fluoaluminate is preferable to one of lower strength. The three applications at 2-week intervals of 70-percent cryolite or undiluted calcium arsenate are made at 20, 30, and 40 pounds per acre, respectively, for a total of 90 pounds per acre, and at 25. 50, and 75 pounds per acre, respec- tively, for a total of 150 pounds per acre. If the cryolite is diluted to contain less than 70 percent of sodium fluoaluminate, the quantity of insec- ticide applied per acre should be increased accordingly. Far example, when a cryolite dusx mixture containing 50 percent of sodium fluoaluminate is used, it should be applied at a total rate of 125 pounds per acre to be equivalent t-i 90 pounds of a 70-percent cryolite. Likewise, if calcium arsenate is diluted with 25 percent of sulfur for tomato russet mite control, it will be necessary to use a total of 120 pounds per acre to get the equivalent of 90 pounds of undiluted calcium arsenate. Three applications *f corn meal bait should be made at 2-week intervals, using 40, 60, and 80 pounds per acre, respectively, making a total of 180 pounds for the season. - 4 - Tomato Pinwo.rm Control Control of the. tomato pinworm may be obtained by using .a cryolite dust mixture containing 7Q. percent of sodium f luoaluminate, with talc as a diluent. When to treaty --In the regular .treatment schedule, the first application ( of cryolite dust .mixture, should be made when the first fruits on the tomato plant are approximately 1 inch, in diameter.. Under unusual conditions or in areas where the pinworm has been causing heavy- losses, a careful watch should be made of the plant bed and »f the newly set transplants, and if a noticeable infestation occurs, an application of cryolite should be made at once. Number of applications. — Whether the plant bed or transplants have been treated or not", the regular treatment schedule, beginning as indicated, should consist. of four applications at 10-day intervals. It is ■ important, however, that the fourth application be made about the time of the. first picking of tomato fruits for the cannery, or after the first picking for market,, and therefore it may be necessary to allow 2 or 3 weeks between the third and fourth applications, depending upon weather conditions. Poundage nf material per acre. — On the basis of 1,000 tomato plants per acre, which is the prevailing planting rate in southern California, the most economical results have been obtained by using a range of from 20 to 25 pounds of the cryolite dust mixture per acre for each application, depending on the size of the plants, or a total of approximately 90 pounds for the four appli-' cations. In any event it is important that the plants be covered thoroughly by the insecticide at each ap.pl ication. Although satisfactory control of the pinworm has been, obtained by using a cryolite dust mixture containing 50 percent of sodium f luoaluminate, experi- ments indicate that, better results can be. obtained with the higher strength unless the quantity of the insecticide applied at the 50-percent strength is increased so that the same number of pounds of the active ingredient, sodium f luoaluminate, is applied per acre. If the 50-percent strength is used, it is suggested that the rate of application range from 25 to 35 pounds per acre per application, or a total of . 125 pounds for the four applications. Tomato Russet Mite ..Control Sulfur is used for the control of this mite. On canning tomatoes, not more than 25 percent of sulfur should be used when there is fruit on the vines, as excess amounts of sulfur might damage the canned product. Undiluted sulfur can be used on small plants before the fruit has set and on larger vines if the fruit is not to be canned. . ... When to treat. — When there is danger of -early infestations (i.e., in later fields and in fields set out. with plants grown in or near old vines or fields), applications of undiluted' sulfur .should be made at or about the third and sixth weeks after transplanting. During the fruiting period of the plants, applications of 25-percent sulfur dust are made at the same time that the fruitworm or pinworm applications are made. If the fruit is not to be used for canning and insecticides are not necessary for fruitworm or pinworm con- trol, undiluted sulfur can be' used for the later applications after the fruit sets. i - 5 - Poundage of material per acre. --From 5 to 10 pounds of undiluted sulfur per ac"re>' per application should be used when the plants are small. From 20 to 50 pounds of 25-percent sulfur dust should be used per acre per application during the fruiting period of the plants when the regular fruitworm or pinworm applications are being made. Number of applications. — In fields that are transplanted before June, 3 or 4 applications of 25-percent sulfur dust made at the time of the fruit- worm or pinworm applications should be sufficient. In fields transplanted in June or later, it is desirable to make 2 additional applications of undiluted sulfur to the small plants at about the third and sixth weeks after trans- planting. Ordinarily it is not necessary to make special or extra applications of sulfur for mite control, as 25 percent of sulfur can be incorporated in the regular dust applications for fruitworm or pinworm control. Previous to these regular dust applications, cutworms, pinworms, flea beetles, or armyworms frequently attack the small plants. In case of such attacks, 25 or 50 percent of sulfur can be incorporated in either calcium arsenate or cryolite used for their control. Joint Control of the Tomato Fruitworm, the Tomato Pinworm, and the Tomato Russet Mite In the event that both the tomato fruitworm and the tomato pinworm are present in injurious numbers in the same field, which is likely to be the case in many fields, a cryolite dust mixture containing 70 percent of sodium f luoaluminate should be used to control these two species of insects. If the tomato russet mite is also present, sulfur should be used as the diluent for cryolite in these applications. Four dustings of this mixture should be applied. The first three applications should be made at 2-week intervals, beginning as soon as the fruits of the main crop begin to set, 20, 30, and. 40 pounds being used per acre per application. The fourth application should be made shortly after the first picking of the fruits for canning, or ordinarily about a week or 10 days after the third application. Twenty-five pounds per acre of the cryolite dust mixture containing 70 percent of sodium fluoaluminate should be applied for this fourth application. The plants should be covered thoroughly by the insecticide at each application. If the pinworm is not a problem and calcium arsenate can be used in your locality without danger of burning the plants, then a dust containing 75 per- cent of calcium arsenate and 25 percent of sulfur can be used. To obtain control of the fruitworm equivalent to the control obtainable with a cryolite dust containing 70 percent of sodium f luoalu-ninate, 30, 40, and 50 pounds per acre of the calcium arsenate mixture should be used for the three applica- tions, respectively. A bait prepared by mixing 9 pounds of corn meal with 1 pound of cryolite containing 90 percent of sodium fluoaluminate is effective in the control of the fruitworm and cutworms. This material is somewhat cheaper than dusting and would be the preferred treatment in localities where the fruitworm is the main pest to be controlled, and in localities where the margin of profit is small and the cost of treatment is a major consideration. (For rate of ~6~ application see page 3)* This material is not effective against the pinworm, russet mite, hornworms, or the "beet armyworm, and should not "be used in localities where these pests usually cause damage. Hornworms. — The regular applications of cryolite or calcium arsenate for fruitworm and pinworm control ordina.rily give satisfactory control of these insects. In cases of severe infestation it may "be necessary to make one or more supplementary applications of undiluted calcium arsenate for the control of these pests. Calcium arsenate has proved superior to cryolite for the control of these insects, and, if a regular cryolite schedule is "being followed for pinworm control, calcium arsenate should be applied in the interval "between the regular applications. If the pinworm is not a serious menace, then calcium arsenate can "be used for one or more of the regular fruitworm applications. Other Insects Cutworms and the beet armyworm may also be present in the same field with the tomato fruitworm, pinworm, hornworms, and russet mite. Ordinarily the rogula.r applications for the control of either the fruitworm or the pin- worm will adequately control these insects, but in epidemic years, or in unusual infestations, special treatments may be necessary as outlined below. Beet armyworm. — This insect usually attacks only tomatoes which mature in the fall, and in ordinary years the rogula.r "worm" applications give satis- factory control of the beet armyworm. In epidemic years of this insect, it may be necessary to make extra applications of undiluted calcium arsenate 'to the plants when they are small and previous to the regular fruitworm or pin- worm applications, and if cryolite is being used in the regular fruitworm or pinworm applications, calcium arsenate should be substituted for cryolite in one or more of these applications, or else an additional application of calcium arsenate for armyworm control should be 'made. In our experiments it has been demonstrated tha.t calcium arsenate is superior to cryolite in the control of the beet armyworm. Cutworms.— In southern California the regular dusting program for the tomato fruitworm has given excellent control of cutworms when they have attacked the plants during the fruiting period. But at times severe infesta- tions will occur on young plants before the time for the regular fruitworm treatment schedule begins. Such infestations must be handled immediately, or many plants will be killed outright. Control can be accomplished by either dusting the plants with 70-PPrccn"k cryolite or undiluted calcium arsenate, or by preparing a ba.it composed of U pounds of paris green, 100 pounds of wheat bran, and sufficient water to make a crumbly mash. Ten pounds of the dust or bran ba.it is sufficient to cover an acre. The dust should bo applied primarily to the stem of the plant, and the bait should be scattered around the base of the plant, preferably in the evening. Sodium fluosilicate may be substituted for paris green in the bait mixture. Warn ing All the materials recommended in this circular are likely to leave insect icidal residues on the fruit if they are applied within 2 weeks of the time the fruits arc harvested. In cases where excess residue is present, the * - 7 - indications are that the washing process_ in the _canneri.es and the process of wiping the fruit for market with a cloth will jjeduce the residue to a quantity well below the dang_er point. _ If_jany insecti_ci_ial materials jar e_ visible on the_ fruit when picked, such_ residue must be removed by wiping or washing before the fruit is offered for sale. CAUTION. — In handling, mixing, and enplying poisonous insecticides care should be taken not to inhale excessive quantities at any time. Well-designed respirators affording protection to the entire face are available and should be used_when such danger exists. After working with insecticides the hands or any exposed parts of the body should be washed thoroughly. Yfriere to Obtain Insecticides Information regarding the purchase of the insecticide materials mentioned in this circular may be obtained usually through local dealers in agricultural supplies, seedsmen, general stores, or through the county agricultural agent, State agricultural experiment station, State department of agriculture, or the Bureau of Entomology and Plant Quarantine, Agricultural Research Adminis- tration, United States Department of Agriculture. UNIVERSITY OF FLORIDA 3 1262 09224 6916