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Vol. 20, No. 6, May 19, 2005 In
this Issue |
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| Insect update |
I have had no reports yet of potato leafhopper, but it generally arrives in |
| Springtails damaging sugar beets again |
For yet another season, globular springtails are damaging sugar beets emerging from the soil. Springtails are tiny (the size of the period at the end of this sentence) soil insects, greenish to purplish-gray in color, that spring when disturbed. They are common in soil, and normally are beneficial, eating decaying plant material, fungi or bacteria, breaking down residue and improving soil structure. On newly emerging beets, springtail damage is rare unless populations are very high (thousands per square foot). This happens most often in fields with moist soil and high residue or in early-planted fields under cool, wet conditions. Fields in areas damaged last year may be at greater risk for damage in this year. Springtails feed aboveground on foliage, damaging the cotyledons as they emerge, and leaving a scraped or scarred appearance on leaves. Last season they were reported to reduce stands in severe cases. There is no defined threshold for this pest in beets, but company agronomists report fields were sprayed. There is very little data on springtail control in crops using foliar sprays – as I said before, springtails are a rare problem. Agronomists report that foliar sprays seem to reduce springtail damage, although none of the foliar insecticides registered for sugar beets list springtails on the label. However, insecticides registered on sugar beet to control other pests can be used against springtails – the site/crop is the legal issue, not the specific pest. These include the following [product name (label rate)]: Asana XL (5.8 to 9.6 oz/acre)** **A caution if tank mixing insecticide with microrate herbicides. Unacceptable crop injury may result from tank mixes of insecticides containing an oil base with microrate herbicide applications. The insecticides above with a double star (**) are emulsifiable concentrates containing an oil base. Use caution when tank mixing these products with herbicides. The best option is to spray the insecticide separately. Although I do not have efficacy data, my sense is that all of these products probably reduce springtail feeding enough to get beets past the cotyledon stage. The difficult questions I cannot answer are: 1) Is the damage attributed to springtails really springtail feeding? Remember, there are other pests damaging beets, such as cutworm or grubs – these cut the beet off before or just as it emerges from the ground. Also, we had frost damage in some locations. Perhaps the damage being attributed to springtails. Is the cost in money and time of spraying springtails translating into increased yield? Clearly this is an area we need to work on in the future. |
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Check for black cutworm feeding Christina
| Black cutworm larvae are feeding – at least in some sugar beet fields. However, Adult black cutworms (moths) migrate into Effective weed control avoids or reduces black cutworm infestations. Controlling low lying, densely growing weeds such as chickweed, deadnettle, and mustards reduces the areas for egg-laying by female moths. If weeds or a cover crop can be killed a week or two before crop emergence, most cutworm larvae will starve. Over the last few years, there have been cutworm problems in corn, beans, and sugar beets, perhaps because of earlier planting or changes in production practices to no-till. Also, there has been a large increase in Roundup Ready crops, so fields may be weedier early in the season. Scout for cutworms at seedling emergence. Look for wilted or cut plants, and dig around the base of nearby seedlings to find the larvae. If you can’t find a cutworm, move down the row to the next apparently undamaged plant. Larvae feed at night and hide during the day, so the best time to look for larvae is in the morning. A general threshold is 5 percent or more of plants showing cutworm damage. Rescue (foliar) insecticide treatments are the preferred way to manage cutworm because few fields will have a significant problem. Insecticides are most effective if sprayed in the evening when the cutworms are active. In crops like corn, beans and alfalfa, pyrethroids such as Ambush, Baythroid, Mustang, Pounce and Warrior are particularly effective against cutworms (Check labels for specific crop registrations and rates.). For sugar beets, options include Asana, Declare and Lorsban. As usual, be careful when adding an insecticide to a micro-rate herbicide application. For good pictures of black cutworm damage in corn, visit: |
| Cold weather stress on corn and soybean Kurt Thelen |
It appears that most of Peter Thomison from Damage from cold temperature stress adversely affected the germination of seeds and the growth of young seedlings and probably predisposed the plants to invasion by soil fungi capable of causing seed rot and seedling blight. In addition to slowing the germination process, cold temperatures, snow and freezing rain from April 20-25 may have caused irreparable harm to the delicate structures of emerging corn seedling. When dry corn seed absorbs cold water as a result of a cold rain or melting snow, “imbibitional chilling injury” may result. Cold water can cause similar injury to seedling structures as they emerge during germination. Such injury in corn seed ruptures cell membranes and results in aborted radicles, proliferation of seminal roots, and delayed seedling growth. When temperatures remain at or below 50 degree F after planting (as they did this year for two weeks) damage to germinating seed is particularly severe. Many of the corn seed planted shortly before the cold temperature stress of April 20-25 have produced seedlings exhibiting symptoms which are characteristic of imbibitional chilling injury (e.g. stunted or aborted radicles).When this physiological damage is combined with surface soil crusting, saturated soil conditions, compacted soils, deep seed placement, and seedling blights, you have a recipe for widespread emergence problems. |
Regional reports 1 – Southeast |
Weather Commodity reports
Corn is struggling to grow and most fields and plants are yellow with some purple and some green color. Based upon past experience, the emerged corn will be light years ahead (with yield) compared to corn not planted yet or later planted corn. Most corn has been planted and most is emerged with advanced fields at only V2. Oats love this weather. Soybeans are also mostly planted, though few fields have emerged. With mid 70’s forecast for the weekend, most soybeans will emerge. Wheat ranges from Feekes 7 to 10 “in the boot.” Some fields look good, nice and even, while others have areas of fields that seem to be going “backwards.” The above growth stage range can be found in the same fields. Some powdery mildew is also present. MiscellaneousThis has been a great May for spring field and planting work. Cool to very cool air temperatures have hampered growth, but farmers are pleased to get their planting completed and have the stuff in the ground. |
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| 2 – Southwest | Weather Commodity reports Seed corn planting is continuing rapidly. Most growers are reporting that they were able to get the inbreds planted with proper delays. Rainfall last weekend in some areas may have created some challenges in isolated locations. The soybean crop is nearly planted in southwest Alfalfa plant height ranges between 16-18 inches. Alfalfa weevil larvae feeding is widespread at this point. Growers should scout, look at their potential harvest schedule and determine if an insecticide application is warranted. Treat if 40 percent of stems show damage and the field won’t be cut for at least seven days. GDD’s Base 41 from around the region as of May 17: Kalamazoo 694, Battle Creek 621, Watervliet 592, Grand Junction 604, South Bend 668, Fennville 538, Niles 597, Coldwater 504, Gull Lake 571 and Allegan 580. MSU recommends harvesting first cutting at 750 GDD’s. Mike Staton reports that the dry weather has had a significant impact on the wheat crop; there are lots of smaller plants and smaller heads this year than normal. Disease pressure from powdery mildew is on the increase in some fields, and has been found on the flag leaf in some instances. The problem seems to be variety specific, varieties that have some resistance to powdery mildew tend to have much less incidence of mildew than those that do not this season. Wheat in the southwest part of the region is in the late boot stage, (Feeke’s stage 10). With the drier conditions and no heavy rainfall events in the forecast, there appears to be less probability of fusarium head scab this year. However, keep in mind that the most vulnerable period for the development of this disease is from now through flowering (Feeke’s 10.5). The window for fungicide treatment for this disease also ends early. |
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| 3 – West Central | Weather Commodity reports Oats have emerged and stands look generally good. Wheat is at Feekes stage 7, although some fields are in Feekes stage 8. We noted few disease problems -- some mildew low in the canopy on susceptible varieties. Corn planting is nearly complete. There is corn that has been planted for more than two weeks and has not yet emerged. Corn that has emerged is generally pale in color and growing slowly. Sugar beets have emerged and most stands are good. Much of the crop has its first leaf pair; some have two fully developed leaf pairs. Little evidence of frost injury has been observed at this time. Soybean planting is 80 percent complete. Emergence has been slow Alfalfa is 12 to 15 inches in height with few problems observed. Grasses have taken advantage of recent rain and cool temperatures to put on rapid growth. Pastures are getting ahead of grazers. Base 41 GGD totals as of May 17 are: |
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| 4 – Central | Weather Commodity reports The soybean crop is 80-90 percent planted. Some of the early planted fields have emerged. The wheat crop is in about Feeke’s 7. We are still seeing some nitrogen applications being made. There is some powdery mildew in the lower parts of the plants. The crop is variable; some fields look very good while others are poor. Scout fields for wheat diseases on a regular basis. The alfalfa crop is 12-14 inches tall. Many farmers are hoping to begin harvest Memorial Day weekend because they are short of feed. Many expect hay supplies to be tight this year due to the number of fields lost due to winterkill. No reports of alfalfa weevil at this time. Scout fields for alfalfa weevil. The oats and barley look very good with no reported problems. |
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| 5 – Thumb | Weather
Temperatures have been near 60 degrees for most of the past week. This weather is causing slow warm up and dry down of soil. Crop growth is also slow due to cool temperatures. Commodity reports A few sugar beets are still emerging and filling in stands. Some stands really needed these additional beets while others had plenty to begin with. Micro-rate herbicide applications have been going on the past couple of days. The most advanced fields now have 4 true leaves but most others have two true leaves. The wheat crop seems to like the cool temperatures also. Most fields are at Feekes 7-8 with just a few flag leaves visible. Some fields are showing nitrogen deficiency. Some fields appear to be improving while others continue to struggle. We finally have some green color on emerged cornfields. Most stands were pretty yellow in their first couple of days following emergence. The most advanced fields are showing their first leaf. Some stands are variable with corn struggling to get out of the ground. Insect feeding on seed and seedlings can be found. This is not a surprise since some fields were planted for four to five weeks before any emergence. Some plants are having problems with unfurling below the surface. Emergence in lighter soil seems faster and more consistent than heavier soil. Soybean planting has had limited progress this past week due to slow drying of the soil. Fields are about 70 to 80 percent planted. A few fields have emerged but most are in the crook stage near the surface and pushing to get up. |
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| 6 – Northern Dave Glenn |
Weather Cool dry weather has allowed field work to continue, but planting has been delayed due to below average temperatures. A number of hard freezes the past week have kept everyone nervous about planting, especially without a good warm up in sight, although Tuesday and Wednesday (May 17-18) were warmer than expected. Soil moisture is still adequate, but rain is needed. There has been just under two inches of rain since April 1, not including 9 inches of snow! Commodity reports Wheat continues to make progress. Some of the 28% put on the past week really burned the plants on top of the freezes. A few soybeans have been put in the ground, but I suspect that this next week most will go in. Alfalfa is finally growing. It is about 6-8 inches tall and looks very good this year so far. Growing degree day totals as of May 18 are 321 at the Hawks weather station. |
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| Weather news | Upper air flow across the upper Fair and dry conditions are expected Friday through Saturday, followed by another chance for showers and thunderstorms late Saturday night continuing through Sunday. Temperatures will approach normal levels the next few days, with highs ranging from the upper 60's to low 70's Thursday through Saturday. Low temperatures will range from near 40 in the north to the low 50's south Thursday morning, warming to low 40's north to near 50 south by Friday. Slightly cooler temperatures are likely again for the first half of next week with the chance for scattered, mainly afternoon and evening showers each day. In the medium range time frame, the latest forecast calls for a return of upper air troughing across the |