EC85-130 A 1985 Guide for Herbicide Use in Nebraska

Extension Circular 85-130: This is the 1985 guide for herbicide use in Nebraska. This circular deals principally with herbicides as an aid for crop production. The suggestions for use are based on results at Nebraska research stations and elsewhere

EC91-130 A 1991 Guide for Herbicide Use in Nebraska

Extension Circular 91-130: This circular is the guide to herbicide use in Nebraska Farming (1991)

EC87-130 A 1987 Guide for Herbicide Use in Nebraska

Extension circular 87-130 is a 1987 guide for herbicide use in Nebraska

NF539 Yield Suppressions of Glyphosate-Resistant (Roundup Ready) Soybeans

Research description and results of testing for effect of glyphosate herbicide application and the effect of the glyphosate-resistant gene in soybean production. Glyphosate is a popular postemergence herbicide. Glyphosate-resistant soybean technology is gaining acceptance in Nebraska and in U.S. cropping systems; however, potential yield suppression from either genetic differences among varieties, the glyphosate-resistant gene/gene insertion process, or glyphosate is a concern. The first of these could contribute to a yield lag; the latter two could contribute to a yield drag. Research Goals We designed experiments to test for both elements of yield drag: the effect of glyphosate herbicide application and the effect of the glyphosate-resistant gene. Since we could not distinguish between yield drag associated with the glyphosate-resistant gene or effects of its insertion, reference to this gene in the following could mean either or both of these possibilities. Two experiments were conducted at each of four Nebraska locations for two years with the intent to: 1) investigate the glyphosate herbicide effect on 12-13 varieties; and 2) look at the effect of the glyphosate-resistant (glyphosate-resistant) gene on five pairs of glyphosate- resistant, nonglyphosate-resistant sister cultivars (eight other cultivars were included as checks). Summary: Yield suppressions were observed. Yield drag from glyphosate application was not observed. Yield drag from glyphosate-resistant gene = 5 percent. Yield lag from variety genetic differences =

NF93-120 The 1993 Atrazine Label Revision

This NebFact discusses the 1993 label revision of Atrazine

INSECT, PLANT DISEASE, & WEED SCIENCE NEWS [No. 87-6] [April 24, 1987]

In This Issue: Musk Thistle Control Book Announcement: SUSTAINABLE AGRICULTURE 1987 Weed Science Tour David Mortensen Joins Staff at Lincoln Musk Thistle Control As the weather warms and the grass greens, musk and assorted other pasture thistles are set to compete, bolt, flower, and scatter seeds across the land. Springing from an innocent-looking flat rosette in late April to a gigantic seed factory in late June, this same scene repeats itself yearly. A robust musk thistle can produce 20,000 seeds. Last summer and fall had ideal weather for musk thistle seed production, germination, and rosette growth. With abundant root reserves, the thistles will be vigorous in 1987. The only effective way to control them chemically is by spraying the rosettes. Once the center stalk elongates, musk thistle has a much higher tolerance for herbicides and is not easily killed. So apply either 2,4-D at 1 1/2-2 qt/A, Banvel + 2,4-D at 0.5 + 1 qt/A, or Tordon 22K at 0.5 pt/A within the next two weeks. Normally May 1 to May 10 are the critical dates for musk thistle bolting across Nebraska from southeast to northwest

Atrazine Degradation in Two Soil Profiles

Two – chloro – 4- ethylamino – 6 – isopropylamino – s – triazine (atrazine) is a herbicide much used throughout the U.S. for control of weeds in corn, sorghum, and nursery crops as well as a temporary soil sterilant. Carry-over of atrazine in soil has caused injury to succeeding crops and until several years ago no residue of atrazine in the topsoil was generally assumed to mean degradation to non-phytotoxic products. However, Burnside et al. showed that leaching can be a significant mode of atrazine dissipation from the surface soil. The question which now arises is what happens to atrazine in the subsoil where factors affecting degradation would differ from those in the topsoil. This research reports studies of atrazine degradation in two soil profiles and the effects of moisture content, microorganism populations, temperature, and adsorption on atrazine degradation. The relative rates and factors influencing the rate of atrazine degradation in two soil profiles were studied in laboratory and field experiments. Advisor: Terry L. Lav

Atrazine Degradation in Two Soil Profiles

Two – chloro – 4- ethylamino – 6 – isopropylamino – s – triazine (atrazine) is a herbicide much used throughout the U.S. for control of weeds in corn, sorghum, and nursery crops as well as a temporary soil sterilant. Carry-over of atrazine in soil has caused injury to succeeding crops and until several years ago no residue of atrazine in the topsoil was generally assumed to mean degradation to non-phytotoxic products. However, Burnside et al. showed that leaching can be a significant mode of atrazine dissipation from the surface soil. The question which now arises is what happens to atrazine in the subsoil where factors affecting degradation would differ from those in the topsoil. This research reports studies of atrazine degradation in two soil profiles and the effects of moisture content, microorganism populations, temperature, and adsorption on atrazine degradation. The relative rates and factors influencing the rate of atrazine degradation in two soil profiles were studied in laboratory and field experiments. Advisor: Terry L. Lav

G1398 Corn Grain Yield and Kernel Weight Stability After Black Layer

This NebGuide disputes previous reports that corn yields are reduced after black layer if harvest is delayed. An October 1995 article in a national farm publication reported that corn dry matter decreased 1 percent for every percent loss in rain moisture as corn dried in the field after black layer (physiological maturity). The dry matter loss reportedly was hybrid specific and possibly due to seed respiration. This observation was based on research conducted at Purdue University with three hybrids over four years. All hybrids tested had significant dry matter losses in three of the four years. A report of similar observations from farmers and agronomists appeared in 1984 in a regional farm magazine. Many farmers have also documented yield losses associated with delayed harvest. If large dry matter losses occur during field dry down, it may be more cost effective to dry grain with artificial heat.. Several researchers have investigated kernel weight and/or yields after black layer. In most of the studies no changes in kernel dry weight were observed following black layer; however, in one report, four of 18 hybrids and five of 42 hybrids studied had changes in kernel dry matter as corn dried from 35 percent to about 15 percent grain moisture. Of the hybrids with dry matter changes after black layer, some had increased dry matter and some had decreased dry matter. These dry matter changes however, were not consistent over years.. Seed respiration is cited as a possible cause for the reported large dry matter losses following black layer. Respiration rates are greatest when grain moisture is near 50 percent and decreases to a minimal level as grain dries to 15.5 percent. These dry matter losses increase with greater temperatures and with greater mechanical damage to kernels. But, with good kernel quality and typical fall temperatures in the corn belt (average daily temperatures ranging between 50°F and 65°F), it would take an estimated 25 to 50 days for 1 percent dry matter loss to occur from respiration. This is far less than the 1 percent dry matter loss reported for every percent moisture loss after black layer