Commercial Field Crop Pest Management

Soybean leaves chewed up and yellowing from slug damage.
Slug damage on soybean leaves.

Commercial Field Crop Pest Management

Guidelines and Recommendations

General Pest Management
 

 

small grains

Sampling Guidelines

Sampling Guidelines

Growth Stage: Seedling (fall), Tillering – Boot Stage (spring)
Pest Sampling Method
Aphids In the fall, examine 1 linear foot of row in 10 sites; estimate the number of aphids per foot of row
Cereal leaf beetle  In the spring,  begin checking for eggs and small larvae on 10 tillers/stems at 10 sites throughout a field, count the number of eggs and larvae per 100 tillers
Growth Stage: Head Emergence to Harvest
Aphids Examine 10 grain heads in 10 sites until the early dough stage, count the number of aphids per head, also note beneficial insect activity
Cereal leaf beetle Examine 10 stems in 10 locations through the early dough stage for larvae and estimate percent defoliation
True Armyworm Starting in early May, examine 5 linear foot of row in 10 sites for the presence of larvae, be sure to examine the area at the base of the plants as well as under crop debris and weeds since the larvae are nocturnal.
Grass Sawfly For initial detection in late April – early May, take 5 sweeps in 5 sites especially along field margins; Once larvae are detected examine five linear foot of row in 10 sites for the presence of larvae; Since larvae feed on the plants during the day, shake the plants in the 5 linear foot of row to dislodge larvae from the plants into the row middles.

Insect Thresholds

 

Growth Stage: Seedling (fall), Tillering – Boot Stage (spring)
Pest Sampling Method
Aphids In the fall, examine 1 linear foot of row in 10 sites; estimate the number of aphids per foot of row
Cereal leaf beetle  In the spring,  begin checking for eggs and small larvae on 10 tillers/stems at 10 sites throughout a field, count the number of eggs and larvae per 100 tillers
Growth Stage: Head Emergence to Harvest
Aphids Examine 10 grain heads in 10 sites until the early dough stage, count the number of aphids per head, also note beneficial insect activity
Cereal leaf beetle Examine 10 stems in 10 locations through the early dough stage for larvae and estimate percent defoliation
True Armyworm Starting in early May, examine 5 linear foot of row in 10 sites for the presence of larvae, be sure to examine the area at the base of the plants as well as under crop debris and weeds since the larvae are nocturnal.
Grass Sawfly For initial detection in late April – early May, take 5 sweeps in 5 sites especially along field margins; Once larvae are detected examine five linear foot of row in 10 sites for the presence of larvae; Since larvae feed on the plants during the day, shake the plants in the 5 linear foot of row to dislodge larvae from the plants into the row middles.
corn growing

Sampling Guidelines

Sampling Guidelines

Growth Stage: Pre-Planting
Pest Sampling Method
White grub, Wireworm Sample one square foot of soil 12 inches deep; one sample should be taken for each 10 acres with a minimum of 5 sites per field; field should not be tilled before samples are taken and soil temperature at 6 inches should be 45-50 degrees F.
Growth Stage: Emergence to Early Whorl
Cutworms Examine 10 plants in 10 locations for the presence of leaf feeding (small irregular holes) and cut plants; also look for live cutworms and estimate the average size of the larvae
Slugs Examine 10 plants in 10 locations for the presence of feeding damage and slime trails; you will need to observe plants at night or during cloudy conditions to actually observe slugs feeding in plants; be sure to also check for slugs under surface trash and in open seed slots
Flea beetles, Cereal leaf beetle, and European corn borer Examine 10 plants in 10 locations, count the number of beetles per plant and percent plants infested for the two beetles; count the percent infested plants for European corn borer, pull the whorls our of 5-10 plants per field to determine the size of ECB larvae as well as the average number per plant
Growth Stage: Mid-Whorl – Tassel Emergence
Stalk borer, True Armyworm, European corn borer, Corn Earworm, Fall Armyworm Examine 10 plants in 10 locations and count the percent infested plants
Growth Stage: Silking
Corn rootworms Count the number of beetles on 5 plants in 10 locations

Insect Thresholds

 

Growth Stage

Pest Preplant Emergence to 4 leaf stage 5 leaf stage to silking
White Grubs 1 per sq. ft.    
Wireworms 1 per sq. ft.    
Slugs 3 per sq. ft. 3-5 per plant  
Cutworms   1-2 leaf – 3% cut or 10% feeding damage 2-4 leaf – 5% cut and larvae present  
Corn flea beetle   5-6 per plant and 50% plants damaged  
Common stalk borer   2 leaf – 4% infested plants 3 leaf – 6% infested plants

4 leaf – 10% infested plants

 
European corn borer   50% plants infested (irrigated)80% plants infested (non-irrigated) 50% plants infested (irrigated)80% plants infested (non-irrigated)
True armyworm   25% plants infested and larvae < 1″ 25% plants infested and larvae < 1″
Cereal leaf beetle     10 per plant and 50% plants damaged
Fall armyworm     75% plants infested with 1 worm or 50% plants with 2 or more worms
Northern corn rootworm *     2 adult beetles per plant
Western corn rootworm *     1 adult beetle per plant


* if both present – divide number of northern corn rootworms by two and add to number of western corn rootworms

a soybean field

Sampling Guidelines

Sampling Guidelines

Pest

Sampling Method

Growth Stage: Seedling to Pre-Bloom

Bean Leaf Beetle, Mexican Bean Beetle Using a drop cloth placed between 2 rows, shake the plants in 6 foot row in 10 sites in a field, count the number of beetles found in 6 foot of row in each site, for Mexican bean beetle note the presence of pupae/eggs at each site, estimate defoliation at each site
Grasshoppers Take 10 sweeps in 10 sites and count the number of adults and nymphs
Thrips Examine 5 leaflets in 10 sites for the presence of thrips, check top and undersides of the leaves
Potato Leafhopper Take 10 sweeps in 10 sites and count the number of adults and nymphs per 100 sweeps, sampling should be done when the foliage is dry
Growth Stage: Prebloom – Podset
Japanese beetle, Green Cloverworm, Silver Spotted Skipper Using a drop cloth placed between 2 rows, shake the plants in 6 foot of row in 10 sites in a field, count the number of insects found at each site and estimate defoliation
 Spider Mites Examine the underside of 5 leaflets in 10 sites for mites; also note the presence of mite eggs and note that amount of damage
Growth Stage: Podset – Maturity
Spider Mites 5 leaflets in 10 locations
Bean leaf beetle, Mexican bean beetle, Green cloverworm, Silver Spotted Skipper, Yellow Striped Armyworm, Beet Armyworm, Fall Armyworm 6 foot of row in 10 sites using a drop cloth
Corn Earworm 5 sweeps in 5 to 10 locations walking down the row

Insect Thresholds

Pest

Sampling Method

Growth Stage: Seedling to Pre-Bloom

Bean Leaf Beetle, Mexican Bean Beetle Using a drop cloth placed between 2 rows, shake the plants in 6 foot row in 10 sites in a field, count the number of beetles found in 6 foot of row in each site, for Mexican bean beetle note the presence of pupae/eggs at each site, estimate defoliation at each site
Grasshoppers Take 10 sweeps in 10 sites and count the number of adults and nymphs
Thrips Examine 5 leaflets in 10 sites for the presence of thrips, check top and undersides of the leaves
Potato Leafhopper Take 10 sweeps in 10 sites and count the number of adults and nymphs per 100 sweeps, sampling should be done when the foliage is dry
Growth Stage: Prebloom – Podset
Japanese beetle, Green Cloverworm, Silver Spotted Skipper Using a drop cloth placed between 2 rows, shake the plants in 6 foot of row in 10 sites in a field, count the number of insects found at each site and estimate defoliation
 Spider Mites Examine the underside of 5 leaflets in 10 sites for mites; also note the presence of mite eggs and note that amount of damage
Growth Stage: Podset – Maturity
Spider Mites 5 leaflets in 10 locations
Bean leaf beetle, Mexican bean beetle, Green cloverworm, Silver Spotted Skipper, Yellow Striped Armyworm, Beet Armyworm, Fall Armyworm 6 foot of row in 10 sites using a drop cloth
Corn Earworm 5 sweeps in 5 to 10 locations walking down the row
alfalfa growing

Sampling Guidelines

Sampling Guidelines

Pest

Sampling Method

Growth Stage: Mid- March to First Cutting
Alfalfa weevil Minimum of 30 stems per field collected in a W-pattern, place stems top first in bucket, measure stem height and count the number of larvae per stem
Pea aphid  Collect a minimum of 30 stems per field and  count the number of aphids and beneficial insects present per stem ( e.g. lady beetles and syrphid fly larvae )
Growth Stage: After First Cutting (mid-May) to September
Alfalfa weevil – only for 2 weeks after first cutting Minimum of 30 stems/crowns per field in a W-pattern, place stems top first in bucket and count the number of larvae per stem/crown
Potato leafhopper Ten sweeps in ten locations – plants should be dry
Blister Beetle 10 sweeps in ten locations<
Garden webworm and other defoliators Estimate defoliation in 10 location

Alfalfa Insect Thresholds

Pest March – April May – early June mid June – mid Sept.
Alfalfa weevil 0-11 in. – 0.7 per stem12 in. – 1.0 per stem

13-15 in. – 1.5 per stem

16 in. – 2.0 per stem

17-18 in. – 2.5 per stem

0-11 in. – 0.7 per stem12 in. – 1.0 per stem

13-15 in. – 1.5 per stem

16 in. – 2.0 per stem

17-18 in. – 2.5 per stem

after 1st cutting – 2 per crown

 
Pea aphid <10 in. – 50 per stem>10 in. – 100 per stem

1 or more beneficials per 50 aphids should provide control

<10 in. – 50 per stem>10 in. – 100 per stem

1 or more beneficials per 50 aphids should provide control

 
Potato leafhopper   3 in. or less – 20 per 100 sweeps4-6 in. – 50 per 100 sweeps

7-11 in. – 100 per 100 sweeps

12 in. or more – 150 per 100 sweeps

3 in. or less – 20 per 100 sweeps4-6 in. – 50 per 100 sweeps

7-11 in. – 100 per 100 sweeps

12 in. or more – 150 per 100 sweeps

Garden webworm / general defoliators     25-30% of tips damaged
Blister beetles     1 per sweep

 

timothy hay

 

 


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