ISSUE 3 May 19, 2005
During the past week (May 11 to 17), the south-central regionís rainfall ranged from 0.2 inches at McHenry to 1.2 inches at Wishek as recorded at NDAWN (North Dakota Agricultural Weather Network) sites. The regionís soil moisture is currently adequate with some areas excessive. The regionís cool-season crop planting is essentially complete with the exception of flax. The majority of corn acres are planted. Soybean planting is in progress, with an estimated 50-65 percent of the acreage planted in counties south of Interstate 94 and about 25-35 percent complete north of I94. Winter wheat is jointing. The regionís spring wheat fields generally have good to excellent plant density and the majority of the crop is in the 1- to 2-leaf stage.
Soybean planting dates
Soybean grown in central North Dakota have performed well when planted during mid May, as indicated by a recent six-year NDSU study at Carrington. During 1999 to 2001, soybean planted during mid-May (May 18 to 21) improved yield an average of 2.3 bushels/acre, or 6 percent, compared with yield from planting during the first week of June. Average yield with 'Traill' (0.0 relative maturity) declined 5 percent when planted late, while yield with 'Daksoy' (00.5 relative maturity) was similar between planting periods.
From 2002 to 2004, soybean planted from May 10 to 15 did not provide a yield advantage, compared with planting 10 to 15 days later (May 20 to 30). Due to a more favorable soil environment for plant establishment, the later planted soybean generally resulted in less time needed for stand establishment, greater plant density and similar date of physiological maturity time, compared with the earlier planting time. However, in one of three times the trial was conducted, 'Barnes' (0.3 relative maturity) had an 8 bushel/acre, or 19 percent, greater yield when planted May 10, compared with May 20, while 'Walsh' (0.0 relative maturity) had a similar yield between planting dates.
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center
Time to Scout for Cutworms with Warmer Weather in Upcoming Weeks
Watch your fields for any cut plants and dig up any cutworm larvae located under cut plants. The wet soil conditions will cause them to feed close to the soil surface making them easy prey for other predators (sea gulls, ground beetles) and easier to kill with insecticides. Fungal diseases could also cause some mortality with cutworms. The cool conditions will slow their feeding activities and larval development. Since there are early and later season cutworms, activity will continue into late June in ND. The Dingy cutworm, Feltia jaculifera, overwinters as a partially grown larva and is one of the first cutworm species to cause problems during crop emergence from early to mid-May. The moth of the dingy cutworm is known to lay her eggs on sunflower heads from mid-July through September. Crops following sunflowers in rotation are at greatest risk of injury by this cutworm.
Other cutworms, the red-backed, Exoa ochregaster, and the darksided, Exoa messoria, overwinter as eggs which hatch in mid to late May. Eggs are laid in the fall and survive in weedy, wet, and reduced tillage areas. Feeding injury by these cutworms normally occurs in late May to early June.
Remember, early detection is critical for effective cutworm control, especially in corn, dry beans, sunflowers, soybeans, sugar beets, alfalfa. Cutworm damage is often localized in certain areas of the field, and in some situations insecticide sprays can be targeted at those infested areas. Economic thresholds include:
Corn: Begin scouting for cutworms when corn is up to a stand and continue until mid-June. Treat when 3 to 6% of the plants are cut and small larvae (<3/4 inch) are present. Application rate of 15 to 20 gallons of water per acre by ground application is suggested.
Dry Bean: Treatment is warranted when one cutworm or more is found per 3 feet of row and the larvae are small (<3/4 inch long).
Forage (Alfalfa): Treatments would be justified when more than 2 worms per square foot are present after the hay has been cut - if larvae are not expected to pupate in the next 3 to 4 days.
Sugarbeets: Cutworm control in young beets is suggested when 4 to 5% cutting of seedlings observed in fields. A population of 3 to 5 per square foot is recommended in late summer and plant canopy is developed.
Soybeans: Economic thresholds for cutworm treatment decisions are not well established. Treatment guidelines used over the years include when one cutworm or more is found per 3 feet of row and the larvae are small (<3/4 inch long). Another guideline is when 20% of plants are cut or when gaps of 1 foot or more exist in the plant row. When making a final decision, consider that surviving soybeans are able to compensate for early stand reductions because of the plants long growth period.
Sunflower: Treatment is warranted when one cutworm or more is found per square foot or there is a 25 to 30% stand reduction observed.
Please consult the 2005 ND Field Crop Insect Management Guide for insecticide registered for cutworm control in specific crops.
Efficacy of Seed Treatments against Crucifer Flea Beetles in Early_planted Canola
This story is becoming all too familiar. We had similar conditions last year! So far, low levels of crucifer flea beetles have been detected on yellow sticky traps at NCREC in Minot. Higher numbers of flea beetles will begin emerging with warmer weather. There is concern with the early-planted canola and whether the commercially applied insecticide-fungicide seed treatment (Helix xtra, Helix lite and Prosper 400) will still control flea beetles. For any early-planted canola that has been in the ground for 21-26 days and barely emerging or in the seedling stage, the residue of the insecticide-fungicide seed treatments will NOT be effective against spring emerging flea beetles! These canola seedlings will be at high risk to flea beetle injury. A foliar insecticide spray will be needed on top of the canola seed treatments as flea beetle feeding activity increases in mid-late May. The economic threshold for flea beetles is 25% foliar damage in seedling canola. Remember, flea beetles can move very fast when weather conditions are warm (>60įF) and quickly defoliate a small canola seedlings when pop. are high.
Registered foliar insecticides for control of flea beetle on canola are: Capture, Decis, Proaxis, and Warrior (pyrethroids) and methyl_parathion (organophosphate). Pyrethroids can be safely tank_mixed with the herbicides labeled in canola. A residual of 7-10 days can be expected from these pyrethroids, only 3-5 days with methyl_parathion. Remember proper timing is very important with foliar sprays!
Flea beetle feeding activity usually continues into late June and has peaked during late May to early June the past several years. When the canola plant is 6-8 leaf stage, it can usually out-grow any flea beetle damage and compensate for feeding injury. However, flea beetles can also cause injury to the center growing point and kill the canola seedling under extremely high populations. Research conducted at the NCREC in Minot, Carrington REC, and Langdon REC over the past several years has shown that a seed treatment plus a Capture (1.3 fl oz/acre) foliar spray applied at 21 days after planting has provided the highest and most consistent canola yields over the years (lowest risk level for those risk-averse producers!) compared to seed treatments alone or a single or double application of Capture. This research was conducted under moderate to heavy flea beetle pressures.
Cool Weather Slows Degree Day Accumulations for Alfalfa Weevil
Degree days for alfalfa weevil continue to slowly climb towards the 250_300 Degree Day (DD) mark (base of 48ļF), which is used to initiate field sampling for alfalfa weevil. Currently, SE North Dakota is the highest with 182 DD accumulated. Further north, DD decrease accordingly with the minimum of 75 DD. The NDAWN website now has a base of 48ļF under Applications and Insect Degree Days, which you can use to access to get the DD accumulations for the state.
2005 Canola Insect Trap Network
Pheromone traps are being put out in canola fields of the north central and northwest regions of North Dakota for the migratory Diamondback moth, and these traps are useful tools for detecting the flights of the adult diamondback moth. Early trap catches are high, >100 moths per trap week in Minot. However, the cold, rainy weather this past week should of cause some mortality with these earlier moths. Weekly trap counts provide good indicators of potential pest problems and the need to scout fields for larvae. Stay tuned for updates as the season progresses.
Leafy Spurge Hawkmoth, Hyles euphorbiae, flying!
The biological control agent, leafy spurge hawkmoth, was observed near Burlington (Ward County) this week, collected by Derrill Fick. This Sphingid moth was introduced and released in the 1980s in North Dakota for control of leafy spurge, Euphorbia escula L. The larvae feed upon the leaves and bracts causing defoliation. By itself, the leafy spurge hawkmoth is ineffective as a biological control agent. Please consult "Moths of North Dakota" NDSU website for pictures of moth and larvae:
Area Extension Specialist
North Central Research Extension Center
The region received from 0.25 to 0.5 inches of rainfall from May 10 to 17, with less rain in northern counties. Southern Nelson county has received more than 5 inches in the last ten days. Good progress has been made in cool season crop planting south of highway 66 and is nearing completion. Planting has been slower north of 66 due to cold temperatures and sporadic light rains. Soybean and sunflower planting has started and corn planting will finish up this week. Earliest planted wheat is in the three leaf stage. Wheat and barley planted the first week of May is emerging. Flax and canola is emerging. No reports of serious freeze damage have been received. Wild oat and early broadleaf weeds are emerging and initial post emergence spraying will start next week on winter wheat and earliest planted spring wheat.
Devils Lake Area Office
A wet heavy snow was received over much of the region on Thursday, May 12. Dickinson had received about 8 inches from this storm with greater amounts falling in more western and southern areas of the region. At least 12 inches fell in the Bowman area. Lesser amounts of snow but more rain fell further east. NDAWN does have a limitation in measuring precipitation when it falls primarily as snow, therefore the amounts currently displayed are conservative and will be adjusted when the data is analyzed. The manually read site at the Dickinson Research Extension Center recorded 1.17 inches of precipitation for the week. At the Hettinger Research Extension Center site, 0.70 inches was reported for the week. Precipitation, whether it fell as rain or snow, was appreciated by most producers.
Tan spot has been observed in winter wheat plantings in the area. Spring wheat growth stage ranges from emerging to the fifth leaf stage. Winter wheat is tillering, canola is in the 2 to 4 leaf stage, and peas are at the 2 to 4 node stage of development. Corn is emerging near Center, ND, 29 days after planting according to Rick Schmidt, Oliver County Extension Agent.
Significant development of alfalfa occurred over this past week though cold morning temperatures of a week ago damaged leaves but not the growing point. Producers are concerned about alfalfa weevil infestations this year due to severe problems the past three years. Larva somewhat similar in appearance to alfalfa weevil has been brought to extension offices in the region, but none of the larva to date is alfalfa weevil. According to NDAWN, the accumulated growing degree_day units for alfalfa weevil (base temp 48oF) are currently at 152 for Dickinson and 125 for Bowman. The feeding damage from larva would not be expected until about 350 to 370. With wet conditions currently delaying field operation, producers will need to adjust herbicide selection and applications in some of their fields.
Area Extension Specialist/Cropping Systems
NDSU Dickinson Research Extension Center