Managing Cover Crops Profitably - Valley Crops Home

Select Covers that Balance Pests, Problems of Farm
Many crops can be managed as cover crops, including cotton, soybean and most
but only a few have been studied specifically vegetables. Rye will not control weedy grasses.
for their pest-related benefits on cash crops Because it can increase numbers of cut worms
and field environments.
and wire worms in no-till planting conditions,
Learn all you can about the impacts of a rye is not the most suitable cover where those
cover crop species to help you manage it in worms are a problem ahead of grass crops like
your situation. Here are several widely used corn, sweet corn, sorghum or pearl millet.
cover crops described by their effects under • Wheat (Triticum aestivum)—A winter
conservation tillage in relation to insects, annual grain, wheat is widely adapted and
diseases, nematodes and weeds.
works much like rye in controlling diseases,
• Cereal Rye (Secale cereale)—This winter nematodes and broadleaf weeds.Wheat is not
annual grain is perhaps the most versatile as effective as rye in controlling weeds
cover crop used in the continental United because it produces less biomass and has less
States. Properly managed under conservation allelopathic effect.
tillage, rye has the ability to reduce soil-borne • Crimson Clover (Trifolium
diseases, nematodes and weeds. Rye is a nonhost
plant for root-knot nematodes and soil-
annual legume throughout the Southeast, fall-
incarnatum)—Used as a self-reseeding winter
borne diseases. It produces significant biomass planted crimson clover supports and increases
that smothers weeds when it is left on the soil-borne diseases, pythium-rhizoctonia
surface and also controls weeds
complex and root-knot nematodes. It
allelopathically through natural weedsuppressing
compounds.
thick mulch. Crimson supports high densities
suppresses weeds effectively by forming a
As it grows, rye provides habitat, but not of beneficial insects by providing food and
food, for beneficial insects. Thus, only a small habitat. Because some cultivars produce “hard
number of beneficial insects are found on rye. seed” that resists immediate germination,
Fall-planted rye works well in reducing soilborne
diseases, root-knot nematodes and
late spring so that it resumes its growth in late
crimson clover can be managed to reseed in
broadleaf weeds in all cash crops that follow, summer and fall.
Soilborne pathogenic fungi limit production of
vegetables and cotton in the southern U.S. (332,
333, 334, 335). Rhizoctonia solani, Pythium
myriotylum, Pythium phanidermatum and
Pythium irregulare are the most virulent pathogenic
fungi that cause damping-off on cucumbers
and snap beans. Sclerotium rolfsii causes rot in
all vegetables and in peanuts and cotton. Infected
plants that do not die may be stunted because of
lesions caused by fungi on primary or secondary
roots,hypocotyls and stems.But after two or three
years in cover cropped, no-till systems, dampingoff
is not a serious problem, experience on south
Georgia farms and research plots shows. Higher
soil organic matter may help.
In soils with high levels of disease inoculum,
however, it takes time to reduce population levels
of soil pathogens using only cover crops.
After tests in Maine with oats, broccoli, white
lupine (Lupinus albus) and field peas (Pisum
sativum) as covers,researchers cautioned it may
take three to five years to effectively reduce
stem lesion losses on potatoes caused by R.
solani (190).Yet there are single-season improvements,
too. For example, in an Idaho study,
Verticillium wilt of potato was reduced by 24 to
29 percent following Sudangrass green manure.
Yield of U.S.No.1 potatoes increased by 24 to 38
percent compared with potatoes following
barley or fallow (322).
30 MANAGING COVER CROPS PROFITABLY