CA1218016A - Control of corn rootworm by application of n-methyl 2- (1-methylethyl) phenylcarbamate - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A method is disclosed for combating the soil insect, corn rootworm which comprises contacting the corn rootworm with an effective amount of N-methyl 2-(1-methylethyl)phenylcarbamate.

Description

5~27}~

CONTROL OF CORN ROOTWO~M ~Y APPLICATIO~
OF N~M~'I`HYL 2~ METII`~I,ETHYL)PHENYLCARBAMAl'~

BACKGROUND OF THE DIS~LOSUR~`
. _ 1. Field of the Invention The instant invention is directed to a method of controlling corn rootworm. Most particularly, the instant invention is directed to a method for combating corn rootworm with an effective amount of N-methyl

2-(1-methylethyl)phenylcarbamate.

2. escription of the Prior Art Corn rootworms are the larvae of several species of beetles of the genus Diabrotica These larvae cause severe damage to the roots of corn plan~s, particularly in fields where one corn crop follows another in succes-sive seasons. The adult beetles lay their eggs in the soil of a maturing crop of corn. The eggs lay dormant in the soil until the following spring. Then they hatch in response to favorable soil temperatures and the 7arvae feed on the roots of young corn plants causing reduction in yield and/or the stalks to topple ovPr when subjected to elther wind or wet soil condi~ionsO The iallen stalks canno~ be sa~isfactorily harvested by mechanical harvesters causirlg significant losses.
One method of con~ating corn rootworm, known in the prior art, is to apply an insecticidally effective amount of N-methyl 3~ methylethyl)phenylcarbamate to the soil around which the corn is planted. This method is disclosed in U.S. Pa~ent 3,25U,673, May 10, 1966 IBagley), It is noted that this reference refers ~o this compound clS 3-.isopropylphellyl N~me~hylcarbamate or meta-isopropylphenyl r7-methylcarbamate (herein call~d MIC). This compound is recited, in the paten~, to be effective, against corn rootworm. The reference further teaches the application of the MIC months after planting of seeds, that is, MIC appiication is a task separate from planting and at a time when the eggs have hatched and the corn has already grown. One of ordinary skill in the art will realize that treating a field of corn that has attained considerable growth is a difficul and time consuming undertaking and may do physical damage to the already existing corn plants. Application rates of from 2-4 lbs/a (2.24-4.48 kg/a) are also mentioned.
The ortho-isomer of MIC is N~methyl 2~ methyl-ethyl)phenylcarbamate ~herein called OIC) a known foliar insecticideO This insecticide, applied directly to plants, is commercially used in the protection of rice crops. However, OIC has never been known to be effec~
tive in the control of soil insects. That is, OIC has never been suggested to be used as a soil insecticideO

SUMMARY OF T~fE INV:ENTION
I t has now been unexpectedly found that N-methyl 2~ methylethyl)phenylcarbamate (OIC~ provides long lasting effective control of corn rootworm residing in the soil wherein corn is plan~ed.
This invention provides several advantages over known methods especially over that taught by Bagley, namely, the compound of this invention has superior resistance to de~rada~ion caused by the influences of a soil environmentO OIC can be applied simultaneously with planting o~ the corn seed, and the one initial application is usually suf f icient for the planting season. OIC may be added to the soil at relati~ely low r~tes while still exerting effective control of corn xootworm over extended period of time, whereas MOC at the same applica~ion rate is ineffective over long peri~ds of time.

~3 ~ he compound of this invention may be applied to the soil for the purpose of contac-ting corn rootworm in forms well known to the art such as a solution in a suitable solvent such as aliphatic alcohols, aliphatic k~tones, and the like, or as a w~ttable powder or an emulsifiable concentrate. Dust and granular forms of OIC may also be employed, a granular form is usually preferred. In the latter case, OIC is dissolved in a solvent and sprayed onto an inert mineral carrier such as attapulgite granules ~10-100 mesh), and the solvent is then evaporated. Such granular compositions may contain from 2 25~ OIC based on the carrier plus OIC, usually 3-15~. In addition, the pesticide may also be incorporated into a polymeric carrier such as polyethyl-ene, polypropylene butadiene-styrene, styrene-acrylonit-rile resins, polyamides, poly(vinyl acetates~ and the like. When encapsulated the OIC may advantageously be released over an even longer time period, extending its effectiveness further than when used in non-encapsulated form.

DETAILED DESCRIPTION

Tn order to carry ou~ this invention, OIC is applied to the soil at a rate of from 0.25-12 lbs~/a (0 28 13.4 kg/ha)O However, it should be considered that in so-called "band" applications, i.e.g when OIC is placed on or into the soil along with seeds as a band approxïmately 2-8 inches (5-20 cm) on each side of the row of seeds, lower rates such as 0.25-3 lbs/a ~0.28-3.4 kg/ha~ may suffice to control corn rootworm. ~hen the compound of this invention is spread in a so-called ~broadcast' fashion, larger doses may be required, such ~s 1-12 lbs/a (1.12-13.4 kg/ha). Usually, 0.5-8 lbs~a ~ca 0.6-10.1 kg/ha) of OIC is needed, i.e., 0.5-2 lbs/a (0.6-2.24 kg/ha~ for band application and about ~-9 lbs/a (7.8-10 kg/ha) for broadcast use.

It is also within the contemplation of this inven-tion that the OIC be added to the soil in combination with other pesticides, as well as plant nutrients, ertilizers and the like.

EX~MPLE 1 Dispersions were prepared having concentrations of 5, 10, 20, 40 and 80 ppm of OIC by adding the required amount of water to a mixture of 100 parts acetone, 6 parts of OIC and 3 parts of surface active a~ent (Emulfor [trademark] EL719, polyoxyethylated vegetable oil).
Similarly, dispersions of MIC having the above mentioned concentrations were prepared in the same manner.
Flower pots having a 3.5 inch (8.9 cm) diameter were each filled wi~h 360 g of dry soil and 40 ml of ~he above dispersions were added to the pots resulting in a concentration of the active ingredient in the soil of 0.5, 1~0, 2.0, 4.0 and 8,0 ppm. The following planting, infestation and evaluation schedule was employed.

Time from Addition of OIC OR MIC
Test Plantin~ Infestation~ ' Scoring __ 1 week immediately~i)1 week 2 weeks 4 weeks 3 weeks(2)4 weeks 5 weeks 6 weeks 5 weeksl )6 weeks 7 weeks Remarks: (1) Two seeds of sweet corn varie y n Silver QueenO"
~2~ Two seeds of sweet corn variety "Pioneer Hibrid~"
~3) Ten third instar larvae of Southern corn rootworm Diaprotica undecimpunctata howardi.
.,r All experiments were conducted with 6 replicates each, including controls which had not been treated with OIC or MIC.

~-s~-Scoring was undextaken by emptying the pots of their 50il, filtering the soil through a fine mesh screen and retaining the larvae presentO The number of live larvae was counted, and percent control of Southern corn rootworn was calculated using Abbot's formula (see J. Economic Entomology 18, 265-267 (1925)).
The results o the experiments are summarized in Table I.

Table I

Test 1 Week 4 Weeks 6 Weeks _ Compound OIC MIC* OIC MIC* OIC MIC*

% Control**
at 8 ppm - - 100 24 93.3 0 4 1~0 88 97.5 11 73 0 2 100 95.3 100 4 ~6 0 1 9~.3 100 57 0 37 0 0.5 79 97.7 * Outside this invention.
** All replicates not including OIC or MIC indicated zero percent control of corn rootworm.

The above results clearly indicate the unexpectedly superior long range efficacy, i.eO, after four weeks or more after insecticidal treatment, of OIC (N-methyl 2~ methylethyl)phenylcarbamate) over MIC ~N-methyl

3-(1-methylethyl)~henylcarbamate~ in controlling corn rootworm.

OIC was dissolved in acetone. The solution was admixed with attapulsus clay~ an inert carrier, ~o form a slur.ry. The s]urry was heated with the resultant evaporation o the acetone solvent and the absorption of the OIC onto the clay. The clay particles were found to contain 4~ hy weight of absorbed OIC, based on the total weight of the particles.
The 4% OIC clay particles were evenly distributed over a plot 10 feet long by 6 inches wide upon which nine newly transplanted cabbage plants were evenly spaced such that the application rate was ~qual to 1 pound of OIC per acre. In a second run the 4~ clay particle application rate was increased such that the effective rate was equal to 2 pounds of OIC per acre.
Each run was duplicated.
The cabbage plants were allowed to grow for 71 days at which time they were dug up and their root structur~ evaluated. Based on standard test evaluation methods it was determined that OIC, at both 1 and 2 pound per acre application rates, was ineffective at protecting the roots of the cabbage plants from attack of the soil insect, Hylemya brassicae, commonly known as cabbage maggot.

Dispersions having concentrations of 100 and 1~000 ppm OIC were prepared in accordance with the procedure of Example 1. Larvae of black cutworm, Agrotis i~s~son, a well kno-~n soil insect, were sprayed, in separate tes s, with the 100 and 1,000 ppm OIC dispersions. This txeatment was ineffec.ive at controlling the larvae~

As stated above, although OIC is a known foliar insecticide, it has never been shown to be effective against soil insects. This is consistent with results obtained by other investigators in their experiences using other foliar insecticides applied against insects residing in the soil. (See U.S. Patent 4,065,558).
Examples 2 and 3 confirm the fact that OIC is ineffec-tive against two well known soil insects. Thus, it is ~11 the more remarkable and unexpected that OIC not only 3~

provides effective control ~ the 50il insect, corn rootworm, but does so over long periods of time.
The aboYe preferred embodiment and examples will make apparent to those skilled in the art other embodi-ments and examples within the scope of the instant invention~ These other embodiments and examples, suggested by the scope and spirit of the instant in-vention, are within the contemplation of this invention.
The invention, therefore, should be limited only b~ the appended claims.

Claims (2)

WHAT IS CLAIMED IS:

1. A method for controlling corn rootworm by contacting said corn rootworm with an effective amount of N-methyl 2-(1-methylethyl)phenylcarbamate.

2. A method in accordance with claim 1 wherein said contact is provided by applying said N-methyl 2-(1-methylethyl)phenylcarbamate to the soil.