POTATO INVESTIGATIONS LABORATORY
Mimeo Report 58-3 October 1, 1957
CONTROL OF INSECTS ATTACKING IRISH POTATOES IN THE HASTINGS AREA1,2
D. M. Norris, Jr.
General Control Considerations
In order to consistently produce a crop of Irish potatoes that will command
the highest current market price, a well organized insect control program must be
conducted. Contrary to some beliefs, such a program consists of a number of other
aspects besides the proper use of proven insecticides at recommended dosages. In
fact, the use of insecticides should, in general, still be considered as a stopgap
control measure. However, it is obvious in the case of a crop such as Irish pota-
toes, which involves a relatively high potential cash return per acre, that all
populations of deleterious insects on the crop must be kept at levels where their
activities do not reduce the yield or damage the quality of the product. In such
a situation, insecticides generally provide the most consistent means to this end.
Nevertheless, the progressive farmer should always do his best to utilize the
following other important methods of insect control:
In the case of potatoes, there are numerous insects; birds; rodents;
other animals; and microorganisms such as fungi, bacteria, and viruses that
are predacious or parasitic upon the insect pests of this crop. If the
farmer is aware of these organisms and does his best to promote their
activities, his need for insecticides will be lessened.
In conducting the various steps in preparing the land; planting,
cultivating, and harvesting the potato crop; and establishing the cus-
tomary summer cover crop, there are certain practices which interrupt
and discourage the life cycles of the various insect pests. A farmer
should be constantly on the alert for ways in which he can alter his
cultural practices to aid in the control of insect pests.
One of the major factors in determining the magnitude of an insect
population is the climate. The upsurge of such a population from a very
low level to a high destructive size is frequently due to a favorable
season from the general climatic and weather standpoint. For example,
relatively dry warm periods generally favor insect multiplication and
wet cool weather usually hampers insect activities. It is therefore
highly important for the farmer to consider these variations in weather
in his insect control program.
1Revision of Mimeo Report 57-3. C
2Portions of the data upon which these recommendations are based are
prepared for publication.
In all major agricultural areas, there are various foras of regular
tions and restrictionU on the ovemant of crop produce. These Iwo are
frequenty concerned with the control of insect pests and are enacted to
aid farers in their battle against insect pests. Because of this, the
taraor daould alUWa oonaem with the w sad a ssist in promoting their
enforcemot here possible.
Toed.cit of Insecticidea to Rmans, Other Animals, and Plants
Insecticides should be handled with repectful caution. In nearly
all cases, the materials that are deadly t~ insect are iikvse deadly
to humans, other animals, and even some plants. Insecticides differ
markedly in their degree of toxicity to various forms of life and there-
fore some must be handled with much more care than others. Parathion,
EFP, systox, EPN, and endrin represent the most toxic extreme in insec.
ticides. While methoxychlor, certain miticides, and plant-derived insec-
ticides such as pyrethrins are classified as of distinctly lesser toxicity.
Nevertheless, these of the latter group are poions and must be treated
as such. In using insecticides, there are two iii s that the grower
should never violate in order to maintain the welfare of all parties con.
cerned. These are as follows:
Follow the instructions on the label of the insecticide container
to the "letter".
This includes the instructions for the safety of the person
applying the insecticide. It pertains to the dosage applied per
acre, and to the established interval that must be allowed between
the last application and harvest in order to assure compliance
with residue tolerances. Laxity in arn of these respects fosters
needless loss of human life, damage to crop plants, production
expense, liability to federal and state reprimand, and possible
confiscation of valuable farm produce.
If there are questions pertaining to any phase of the use of insec-
ticides consult a specialist in entomology before proceeding.
Such persons should have the needed information at hand or know
where to obtain it and thus avoid complications that may result from
careless use of these poisons.
Potato Insect Control Program
During the past several years, the wireworm, Conoderus fall Lane, has
become very difficult or nearly impossible to control in cert fields.
This severe problem is apparently due to the development of resistance in
wireworms to the soil insecticides used in this area. Thus, the materials
that used to kill the wireworms no longer do the job. As a result, no
especially good chemical control measure is available for wireworm control
this season. However, several insecticides still provide control under
certain conditions and are thus conditionally recommended in Table 1 below.
In applying insecticides to the soil, the main problems are as follows:
(1) using the proper dosage (See Table 1) (2) making treatment at proper
time(2-3 weeks prior to planting), and (3) applying insecticide in the
proper manner(disking in immediately afterwards). In spraying insecticides
on the soil be certain that the nozzles are placed on extensions which place
them within 6 inches of the ground surface and are arranged so the entire soil
surface is covered uniformly. The use of a pressure of only 100-150 lbs. will
reduce the amount of spray lost in the air. Be sure the spraying operation
is done when there is little or no wind and disk and/or rebed immediately.
Use 1 quart of 25% DDT emulsion and 1.2 pints of 25% para-
thion emulsion(or J-1 pint of a 50% parathion concentrate) in
100 gallons of water per acre. Spraying with this combination
about every 10 days will generally provide satisfactory control.
Apply a mixture of 5% DDT and 2% parathion dust at the
rate of 20-30 lbs. per acre every 10 days.
Regular spray applications should begin when the first aphids or
other foliage feeders appear. These materials may 'e combined in the
same spray solution with the fungicides used to control late blight.
The use of the insecticides recommended for control purposes on
potatoes involves no poison residue problems. In case some other material
is to be used, it is suggested that its status with regard to residue
tolerances be clearly understood and honored.
Table 1.- Common Insect Pests of Irish Potatoes in the Hastings Area
Insect Insecticide 100 gals./A or General Statement
total dust/A _
Aphids 25% parathion emulsion 1-2 pints
2% parathion dust 20-25 Ibs.
25% 'DDT emulsion 1 quart Controls small infestations
Cutworms 70% toxaphene emulsion 1-2 pints Frequently bother young
1 toxa- ene dutI newly emerged potato plants
10g toxaphene dust 2^30 lba.-
25% DDT emulsion 1 quart
____._. DL4T dust 25-30 Ibs. _____
Leaf-footed 25% parathion emulion 1-2 pints
plant bug, 2%parathion dust 25-30 lbs.
green stink bug ~72chlordane emulsion 1 pint
Serpentine 25% .arathion emulsion 1-2 pints
leaf-miner 2% parathion dust 20-30 lbs. ___
Wireworms IAldrin emulsion Apply as discussed above in
(2 Ibs. actual/gal.) 2 gals. portion under soil insect
1(2 Ibs. actual/gal.) 2 gals.