| Pest | Effect* | Notes |
|---|
| Aphids |
- to 0 |
Prior crop residues may decrease the attractiveness of new stands of wheat
to airborne aphids in the fall. Seeding wheat after Hessian fly-free dates
avoids most fall infestations of aphids. |
| Armyworm |
0 to +++ |
Grass cover crops attract egg-laying armyworm moths. Because the grass
cover crop is not plowed under in no-till, larvae can move from the grass
to feed on corn. |
| Black Cutworm |
+ to +++ |
Adult cutworm moths prefer to lay eggs in weedy fields and in fields with
unincorporated crop residues. |
| Corn Rootworm |
0 |
Adults lay eggs in summer; subsequent tillage has little effect on egg
survival during most winters. In harsh winters with subnormal temperatures
and subnormal snowfall, egg survival is somewhat greater with reduced
tillage. |
| European Corn Borer |
0 to + |
Conservation tillage favors greater survival of corn borers in crop
residue, but effects in specific fields are minor because moths disperse
for emergence sites to lay eggs in suitable fields throughout the local
area. Where planting is delayed or emergence slowed (cooler soil
temperatures), corn may be less susceptible to attack by first generation
corn borers and more susceptible to second generation damage. |
| Grasshoppers |
0 to + |
Reducing tillage favors the survival of only those species that lay eggs
within fields. Those that lay eggs in weedy margins are not affected. |
| Hessian Fly |
0 to +++ |
Fly populations carry over where wheat stubble is not tilled and volunteer
wheat is not controlled. Hessian flies from undisturbed stubble move to new
wheat that is planted before fly-free dates. Hessian flies that infect
volunteer wheat in the late summer and early fall overwinter in the
volunteer plants and can move to additional fields in the spring (regardless
of those fields' fall planting dates). No-till seeding of wheat into other
crop residues poses no problems. |
| Russian Wheat Aphid |
0 to ++ |
Favored by presence of volunteer small grains. Adjusting planting dates is
a more important cultural practice than modification of tillage. |
| Slugs |
+++ |
Unincorporated crop residues and cooler, wetter conditions favor increases
in slug population and potential damage. Available chemicals do not provide
effective control of slugs or are prohibitively expensive (even when
banded). |
| Spider Mites |
- to + |
Where crop residues slow soil moisture losses, plants may be less
drought-stressed than in plowed fields. Reducing drought stress slows
spider mite outbreaks. |
| Stalk Borer |
0 to +++ |
Overwintering survival is greatest in conservation tillage systems. In
no-till fields, damage is most likely where grasses were present to attract
egg-laying moths the previous August or September. If corn is no-tilled
into soybean stubble where weeds were controlled during the previous year,
stalk borers will not be a problem. |
| Stink Bugs |
+ to +++ |
Brown and one-spotted stink bug adults overwinter under crop residue and
other protected sites. Preferred overwintering sites include wheat or rye
cover crops. Corn seedlings are at risk if planted no-till into a grass
cover crop. |
| Wheat Curl Mite |
0 to ++ |
Similar to Russian wheat aphid since volunteer wheat management and
adjustment of planting date are key cultural practices. |
| White Grubs |
+ |
Increases in grassy weed populations and reduced disturbance of the soil
favor survival. |
| Wireworms |
+ |
Grassy weed populations, reduced soil disturbance, and delayed germination
caused by cooler soil temperatures may favor wireworm buildup and
damage. |
* The range of effects notes the possibilities and worst case scenarios. Individual field experience may not confirm these
extremes. Weather is directly tied to potential pest problems in no-till.
- = decreased pest population, 0 = no effect, + = some increase, ++ = increase,
+++ = substantial increase. |
