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XIV. Pasture
and Forage Insects
G. D.
Buntin, R. D. Hudson, and W. A. Gardner
Acreages of forage
and pasture crops have declined in recent years to about 1.3 million acres of grass
pastures and an additional 600,000 acres of grass hay pastures in 1996. Although
losses per acre generally are low and treatment thresholds are large, this extensive
acreage produces large combined losses for forage and pasture insects in Georgia.
Losses are greater for hay than pastures because hay crops have greater yield potential
and market value.
Rainfall was below
normal which reduced forage yields later in the summer. The number one pest of
perennial grass forages, primarily bermudagrass was mole crickets. Mole crickets
damaged grass pastures in southern Georgia especially in the Flatwoods region often
requiring replanting. Mole cricket damage has declined in some fields in four counties
where the parasitic nematode Steinernema scapterisci has been released. The
white grub complex, mostly Phyllophaga spp., Cyclocephala sp. and Green June
beetle larvae caused damage in some fields, with damage levels not changing much from the
previous year. Green June beetle larvae were particularly damaging to fescue
pastures in northern Georgia. Fall armyworm and the 2-lined spittlebug caused damage
in some fields.
Alfalfa acreage in
Georgia was about 30,000 acres on 1996. The alfalfa weevil was the number one
pest of alfalfa with most fields being treated to control this insect. Dry weather
induced damage by the potato leafhopper in some fields.
Estimates of Losses and Control Costs
Rank |
Insect |
Cost of Control |
Damage |
Total |
| |
GRASS HAY PASTURES |
|
|
|
1 |
Mole crickets |
$360,000 |
$6,525,000 |
$6,885,000 |
2 |
White grubs |
420,000 |
792,000 |
1,212,000 |
3 |
Fall armyworm |
60,000 |
54,000 |
114,000 |
4 |
Two-lined spittlebug |
42,000 |
54,000 |
96,000 |
| |
Subtotal |
$882,000 |
$7,425,000 |
$8,307,000 |
| |
GRASS PASTURES |
|
|
|
1 |
Mole crickets |
$468,000 |
$3,253,000 |
$3,721,000 |
2 |
White grubs |
910,000 |
629,000 |
1,539,000 |
3 |
Fall armyworm |
130,000 |
43,000 |
173,000 |
4 |
Two-lined spittlebug |
91,000 |
43,000 |
134,000 |
| |
Subtotal |
$1,599,000 |
$3,968,000 |
$5,567,000 |
| |
ALFALFA |
|
|
|
1 |
Alfalfa weevil |
$189,000 |
$403,000 |
$592,000 |
2 |
Potato leafhopper |
0 |
36,000 |
36,000 |
| |
Subtotal |
$189,000 |
$439,000 |
$628,000 |
| |
Grand Total |
$2,670,000 |
$11,832,000 |
$14,502,000 |
|
Information Pertaining to Control of Major Pasture and Forage Insect
Pests in Georgia |
Insect |
No. Acres Needing Control |
Total No. Acres Treated |
Avg. Cost Per Unit Treated1 |
Tons Loss on Units Treated |
Tons Loss on Units Not
Treated |
GRASS HAY PASTURES |
|
|
|
|
|
Mole crickets |
192,000 |
30,000 |
$12.00 |
7,500 |
101,250 |
White grubs |
60,000 |
42,000 |
10.00 |
4,200 |
9,000 |
Fall armyworm |
12,000 |
6,000 |
10.00 |
150 |
750 |
Two-lined spittlebug |
12,000 |
6,000 |
7.00 |
150 |
750 |
GRASS PASTURES |
|
|
|
|
|
Mole crickets |
260,000 |
39,000 |
12.00 |
3,900 |
55,250 |
White grubs |
130,000 |
91,000 |
10.00 |
3,640 |
7,800 |
Fall armyworm |
26,000 |
13,000 |
10.00 |
130 |
650 |
Two-lined spittlebug |
26,000 |
13,000 |
7.00 |
130 |
650 |
ALFALFA |
|
|
|
|
|
Alfalfa weevil |
28,500 |
27,000 |
7.00 |
2,160 |
1,200 |
Potato leafhopper |
1,500 |
0 |
7.00 |
0 |
300 |
|
| NOTE: Hay crops consisted of 600,000 acres of grasses (hybrid bermudagrass 75%;
tall fescue 20%; and other grasses 5%), with an average yield of 2.5 tons per acre.
Alfalfa acreage was 30,000 acres with an average yield of 3.5 tons per acre. Grass and
clover hay were valued at $60 per ton and alfalfa hay was worth $120 per ton. Permanent
pasture consisted of 500,000 acres of bahiagrass and 800,000 acres of fescue,
fescue/clover mixtures and fescue/common bermudagrass. Average yield was estimated at 1.0
ton per acre with a value of $55 per ton. An additional 400,000 acres of temporary pasture
(mostly small grains and sorghum) was grazed. There was 150,000 acres of sorghum, and
millet silage was harvested. Silage and temporary pasture crops were included as pasture
grasses (Troy Johnson, Extension Agronomist, Athens, GA, personal communications).
1 Application cost not included. Unit = 1 acre |
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