Southwest Michigan field crop regional report – June 2, 2014
Crops are progressing nicely. Make decisions about whether to use fungicides on wheat now. Wet weather in the forecast may mean trouble with head scab for wheat that is just beginning to have heads emerge.
Field conditions and weather
Excellent field conditions over the last several days have pushed planting towards completion in the southern sandier zones. Heavier soils continue to have some delays, especially in Allegan County that received heavy rainfall about a week ago. Warmer conditions have really spurred on growth and development of crops. Growing Degree Days are accumulating rapidly. GDD's Base 50 since May 1st in Three Rivers are at 191. We typically accumulate between 12.6 and 13.4 GDD's per day over the next 10 day period. Warmer and wetter than normal conditions are expected in the 6-10 day outlook, with a return to more normal precipitation levels during the 8-14, but with warmer conditions remaining. All in all, growers here are relieved to see much improved conditions compared to the slow start during the spring.
Rainfall totals for the week for the 13 Michigan State University Enviro-weather stations in the southwest averaged 0.69 inches, ranging from 1.65 inches at Berrien Springs to 0.18 inches at South Haven. The south-central stations averaged 0.66 inches, ranging from 1.77 inches near Kalamazoo to 0.25 inches in Charlotte. Overall soil moisture conditions have been very favorable for early growth. We did, however, begin to put water on to aid germination of late-planted seed corn and soybeans on sands on Tuesday (May 27). Pounding rainfall in Allegan and southern Cass counties caused erosion and may have caused drowned out areas in some fields.
Commercial corn planting is nearly complete on the sandier fields, and not too far off on other soil types as well. The exception would be areas in Allegan and northern Van Buren counties that had been hit hard by heavy thunderstorm rainfall and remain wetter than the rest of the region. Corn ranges from approaching V3 in advanced fields in Branch and St. Joe County to not yet emerged. The majority of fields are between V1 and V2 (Mothers Day weekend planting window).
Growers should continue to think about scouting for black cutworm and armyworm in corn, seed corn if there was green material in fields following Mothers Day weekend. It takes 300 GDD's for clipping to begin from egg laying, so it is early yet to expect to see damage. There have been reports of limited damage in a field in Berrien County.
Weed control windows have been limited by wind, so some fields are behind. Early planted corn is reaching the 5 inch mark, which begins to separate out which materials can be used as delayed pre-emergence sprays. Be sure to consult Table 1G in MSUE Bulletin E-434 Weed Control Guide for Field and Forage Crops, to check for maximum corn heights for delayed pre-emergence weed control programs (Page 47). Warm temperatures will push both corn and weed growth on quickly, so keep the spray window in mind. Purdue’s corn agronomist reports that it takes roughly 82 GDD's Base 50 to move to the next exposed leaf collar from emergence to V10.
Soybeans are growing rapidly. Stages range from V1 to not yet emerged, with lots of beans at the unifoliate growth stage now. Some of the early planted beans that went into cold ground have been slow to emerge, but generally are still coming up. Beans that were planted into warm, moist soils are up and growing well. There is no sign of soybean aphids in fields I have walked.
The most advanced wheat field I know of is fully headed out (Feeke's 10.5) and ready to flower. Most fields are behind this growth stage by at least a week. There are very low levels of leaf diseases in fields that I have walked. I did not see signs of armyworms in this advanced field either. We did catch 2 armyworm moths in a trap in Van Buren County, but it was just put out last weekend. Warmer and drier weather as of late should reduce leaf disease pressure, but rain in the forecast following the weekend might put some of the earlier flowering fields at risk for head scab. You can use the PSU Fusarium Head Blight Prediction model to help determine if your fields should be at risk as they approach flowering. See recent article about using fungicides to suppress Fusarium head scab in wheat.
In seed corn, splash-and-dash showers continued to make "hitting the nick" with proper planting delays a challenge this last week. Overall, the seed corn that is up, is looking very good. Planting is continuing at a good pace. Watch for armyworm in late destroyed cereal cover crops as the season progresses.
Alfalfa first cutting is being harvested in earnest right now. Some hay got a little wet at the end of the last cutting window. Overall the crop is a little shorter than normal, but still should yield respectably. Alfalfa weevils are beginning to gain some momentum now in several fields, so if harvest is going to be delayed, fields should be scouted for the pests. Also, check the re-growth as this pest can cause issues in the second cutting. Treatment thresholds from MSU Extension Field Crops Entomologist Chris DiFonzo in bulletin E-1585 are as follows:
Scouting for Feeding - Before first cutting, sample 20 stems in 5 different locations of the field, look for larvae and damage. Threshold: Before first cutting, 40% of stems damaged, plus live larvae present. After first cutting, check stubble or regrowth for larvae; after first cutting, 25% or more of new tips damaged, or 6 to 8 larvae per square foot of regrowth.
Stem-and-Bucket method - Pick 10 stems randomly as you walk. Place them upside down in a bucket. Shake vigorously to dislodge large larvae, then pull apart the stem tips to find small larvae missed by shaking. Threshold: alfalfa less than 12 inches = 1 or more larvae per plant; 12-16 inch alfalfa = 2-4 larvae per plant; 16+ alfalfa = consider cutting. Check re-growth for larvae.
Snap bean and pickling cucumber planting are underway with the warmer temperatures, as well as tomato and pepper transplanting.
Early planted potatoes are growing rapidly. Irrigation had started earlier in the week to maintain soil moisture in the root zone.
What's next in pest development
European Corn Borer (ECB) remains an insect of interest primarily because of the acreage of seed corn in southern Michigan and for those that have regulatory obligations to apply insecticides when exporting plants out of the region. Dr. Eileen Cullen, University of Wisconsin field crops entomologist, reports that ECB growth and development models reference first spring moth flight occurring around 375 Base 50 GDD's accumulated since January 1st. First egg laying would be expected to occur around 450 GDD's. Peak first generation moth flight may occur around 630 GDD's. The first generation treatment period usually ranges between 800 and 1000 GDD's Base 50. A quick review of the Base 50 heat accumulation at Mendon and Coldwater show 574 and 464 respectively.
Other Michigan State University Extension field crop regional reports from this week: