STATE PLANT BOARD
April 1943 E- 39
United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine
THE CONTROL OF THE TOMATO FRUITWOPR, 1/THE TOT"ATO PIMWOR", THE T0"ATO RUSSET 77TE, AD TTOEWOPUS
By Joseph Wilcox and J. C. Elmore, Division of Truck Crop Insect Investigations
Tomato plants and fruits are attacked commonly by several species of
insects, and important among these are the tomato fruitworm, the tomato pinworm, 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 (Helinthis armigera(Hbn.)), also known as the corn
earworm on corn and as the bollworm on cotton, is a pest of tomatoes, regularly 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 lycopersicella (Busck)) is a pest of
tomatoes in southern California. It is known to occur in Arizona, Niew Mexico,
Missouri, Florida, Mississippi, Virginia, Delaware, and Pennsylvania. In
addition to tomatoess this insect also occasionally attacks potato and eggplant. In California, Arizona, 1ew Mexico, and Florida the tomato pinworm has been primarily a pest of field-grown tomatoes, whereas thus far in Mississippi,
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
The tomato russet mite (Phyllocoptes destructor Keifer) was first found
in Modesto, Calif., in 1940. By 1941 it had spread over most of the San Joaquin and Sacramento valleys and in 1942 it was widespread in southern
California. Besides tomato, other host plants recorded by the University of California are 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.
1/ This supersedes Circular E-489, Suggestions for the Control of the
Tomato Fruitworm, which was issued in Seotember 1939.
There are two species of hornworms that attack tomatoes--the tomato hornwmrm (Protoparce uinquemaculata (Haw.)) and the tobacco hornworm (P. sexta (Johanj), which are widely distributed over this country. In certain sections they are, unless controlled, very destructive. They feed on the foliage of the plant, first attacking the leaves, oftentimes stripping the plants to thepoint where pnly the main stalk or stems remain.
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 tomato fields may be infested at some period during the same season with the tomato fruitworm, the tomato pinworm, hornworms, the tomato russet mite, Putworms, 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 arsenste dusts ard 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.
Cryolite.--Extensive experiments have demonstrated that this insecticide is one mf 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 erynlite is sodium fluoaluminate. 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 fluoaluminate content and at the same rate per acre. For example, the same control can be expected from the use of a total of 180 pounds per acre of cryolite dust containing 35 percent of sodium fluoaluminate as can be expected from the use of a total nf 90 pounds per acre mf a cryolite dust containing 70 percent of sodium flunaluminate. As it is cheaper ti mix and apply 90 pounds of a dust containing 70 percent of sodium fluoaluminate 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 arsenae (undilute is as effective as a cryolite dust containing 70 percent of sodium fluoaluminate when both materials ate used at the same rate per acre. Calcium arsenate also has the added advantage of being cheaper than oryolite and in being more effective than cryolite in the control of hornworms and the best armyworm. CalciLun 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.
Corn meal bait.--This bait is prepared by mixing 9 pounds of corn meal (as finely ground as for pout ry 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 of the fruitworm as a total of 90 pounds per acre of.a cryolite dust containing 70 percent of sodium flucaluminate, 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 sppciail 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 fruitworm control should be made as soon as the fruits of 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 1/2 inch in diameter or less. The 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 fluoaluminate, 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 of 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 percent 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, respectively, 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 insecticide applied per acre should be increased accordingly. FMr example, when a cryolite dust mixture containing 50 percent of sodium flucaluminate is used, it should be applied at a total rate of 125 pounds per acre to be equivalent ti 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.
ThrP applications Af 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.
Tomato Pinrworm Control
Control of the.tomato pinworm may be obtained by using a cryolite dust
mixture containing 7Q percent of sodium fluoaluminate, with talc as a diluent.
When to treat,.--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 ef the newly set transplants, and if a noticeable infestation occurs, an application eof 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 f6urth applications, depending upon weather conditions.
Poundage of 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 applications. In any event it is important that the plants be covered thoroughly by the insecticide at each application.
Although satisfactory control of the pinworm has been obtaine-d by using
a cryolite dust mixture containing 50 percent of sodium fluoaluminate, experiments indicate that better results can be obtained with the higher strength unless the quantityof the insecticide applied at the 50-percent strength is increased so that the same number of pounds of the active ingredient, sodium fluoaluminate, 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 plhts, applications of 25-percent sulfur dust are made at the same time that the fruitworm or pinworm applications are made. If the frtit-is not to be used for canning 'and insecticides are not necessary for fruitworm or pinworm control, undiluted sulfur can be' used for the later applications after the fruit sets.
Poundage of material per acre.--From 5 to 10 pounds of undiluted sulfur per acr 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 pinvorm 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 fruitworm 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 transplanting.
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 army-wuorms 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 flunaluminate 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 dustinrs of this 1m.ixture 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. Pwenty-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 calcitur arsenate can be used in your locality without danger of burning the plants, then a dust containing 75 oercent 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 flucaltminate, 30, 40, and 50 pounds per acre of the calcium arsenate mixture should be used for the three applications, 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
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 ordinarily give satisfactory control of these insects. In cases of severe infestation it may be necessary to make one or more supplementary applications of unrliluted 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.
Cutworms and the boot armyworm may also be present in the same field
with the tomato fruitworm, pinworm, hornworms, and russet mite. Ordinarily the regular applications for the control of either the fruitworm or the pinworm will adequately control those insects, but in epidemic years, or in unusual infestations, special treatments may be necessary as outlined below.
Beeoot armyworm.--This insect usually attacks only tomatoes which mature
in the fall, and in ordinary years the regular "worm" applications give satisfactory control of the booeet 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 r-gular frinitworm or pinworm 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 that calcium arsenate is superior to cryolite in the
control of the boeet armyworm.
Cutworms.--In southern California the rcgulo. dusting program for the tomato fruitworm has given rl:collent control of cutworms 1hen they have attacked the plants during the fruiting period. But at times severe infestations 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-percent cryolite or undiluted calcium arsenate, or by propering a bait composed of 4 pounds of paris green, 100 pounds of wheat bran, and sufficient water to make a crumbly mash. Ten pounds of the dust or bran bait is sufficient to cover an acre. The dust should be applied primarily to the stem of thle plant, and the bait should be scttered around the base of the plant, preferably in the evening. Sodium fluosilicate may be substituted for paris green in the bait mixture.
All the materials recommended in this circular arc likely to leave
insecticidal residues on the fruit if they are applied within 2 weeks of the time the fruits are harvested. In cases where excess residue is present, the
indications are that the washing process in the canneries and the process of wiping the fruit for market with a cloth will reduce the residue to a quantity well below the danger point. If any insecticidal materials are visible on the fruit when pi cked, such residue must be removed b. wiping or washing before the fruit is offered for sale.
CAUTION.--In handling mixin, and nplin7 poisonous irsecticides care
should be taken not to inhale excessive qu -,rtitics at ny time. .Well-desi ned 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 bodg should be washed thoroughly.
Where 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 Administration, United States Department of Agriculture.
UNIVERSITY OF FLORIDA 3 1262 09224 6916