Report on the Agricultural Experiment Stations, 1953 Page: 106

                                
106         REPORT ON EXPERIMENT STATIONS, 1953
tana alone. By continuing its research the Montana station has discovered
that more than one insecticide is effective in weevil control
and the cost of treatment has been reduced from $5.50 to $2 per acre.
In the acreage treated in Montana, savings on cost of treatment approximated
$250,000 in 1 year.
Control of Meadow Spittlebug on Legumes
The Indiana station has shown that alfalfa may be selected for degrees
of resistance or attractiveness to the meadow spittlebug. Alfalfa
selection C40 had a low population of nymphs (61 per square foot),
whereas selections C42, A220, and A230 had very high populations
(257, 205, and 222 nymphs per square foot). Alfalfa, although attractive
to large spittlebug populations, may be selected for tolerance.
Two selections had infestations of 124 and 158 nymphs per square
foot and still produced 1.36 and 1.41 tons of hay per acre. Alfalfa
selections may also be relatively intolerant to low spittlebug populations.
For example, the varieties Atlantic and Washington, had infestations
of 128 and 103 nymphs per square foot and produced 0.94
and 1.01 tons per acre, respectively. Although these yields are relatively
low, they indicate the possibility of selecting varieties of alfalfa
that are resistant or tolerant to meadow spittlebugs. This is good
news, as experimental results have shown reductions in forage yields
ranging from 20 to 50 percent when infestations were heavy.
In research on chemical control of meadow spittlebug, the Ohio
station, as previously reported, has found that increases in hay yields
of 25 to 30 percent were obtained after spraying to control this pest on
legumes. The continued research on the control of spittlebugs has
shown that fall applications of DDT, made early in September, reduced
adult spittlebug populations an average of 83.7 percent and resulted
in an average reduction of 94.8 percent in the number of nymphs
the following year. Methoxychlor also gave promise of good results
especially if treated forage is to be fall pastured. Fall applications of
DDT or methoxychlor were inferior to springtime treatments of BHC
or toxaphene but were satisfactory in reducing nymph populations to
noneconomic levels. Fall applications had the advantages that the
fields were then in better condition, the farmer's work load was less, no
insecticide such as BHC that might contaminate succeeding root crops
was used, and the possibility of an insecticidal residue on the finished
bay was avoided.
Aphid Control Increased Alfalfa Yield
The Kansas station in research to protect alfalfa from insect pests
found that pea aphid control increased the yield of hay from 2 to 2.5
times over check plots where aphids were not controlled. In the experimental
field of Buffalo alfalfa on the day before the insecticides
were applied, 5 sweeps with a collecting net captured from 2,554 to
3,566 aphids per plot. The check plots averaged 2,824 aphids per plot.
Twelve insecticides were tested and 5, including DDT, gave good control.
Infestation dropped on the untreated check plots to 2,074 aphids
on the fourth day following treatment and the number of aphids on
the DDT-treated plot was 68, which was 97 percent control.