Typescript (photocopy). / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries

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No description available.

Two varieties of sideoats grama (Vaughn and NM-28) were planted in late summer of 1980. The seedlings were treated with a variety of broadleaf weed control treatments at 1-, 3-, 5-leaf, and tillering stages of grass seedling growth to determine the effectiveness of these treatments for controlling weeds and the appropriate stages of grass seedling growth to apply them and consequently on grass establishment, density, forage production and plant height. Four months after seeding, NM-28 stands were more dense, produced more forage and the plants were taller than Vaughn. Treatments of dicamba at 0.28 and 0.56 kg/ha were the most effective herbicidal treatments in controlling weeds and resulted in highest stand densities and yields when applied at the 1- and 3-leaf seedling growth. Both treatments gave over 90% control of weeds at the earlier stages but control decreased at later stages of treatment. Lower control resulted when 2,4-D at 0.56 and 1.12 kg/ha were applied. Even though hand weeding treatment resulted weed-free plots during the first four months of seedling development, it resulted in less stand densities and yields when compared to herbicidal treatments. One year after treatment, Vaughn established into taller stands and produced higher yields than NM-28. Dicamba 0.28 kg/ha and 2,4-D 0.56 kg/ha effectively aided in better stand density and yield. Treatments applied at earlier stages of growth resulted in better establishment of both varieties. Dicamba at 0.28 kg/ha was the most effective herbicidal treatment for both varieties. However, hand weeding evaluated one year after seeding, effectively increased both accessions' yield and was the most effective treatment. Greenhouse and laboratory experiments were conducted to determine the uptake and distribution of ('14)C-2,4-D in both sideoats grama accessions and palmer amaranth seedling plant parts at 1, 4, 8 and 24h after treatment. Over all harvest times, 25.3, 2.8 and 3.1% activity were recovered in Vaughn treated leaf, tillers and crown, respectively. That was compared to 33.9, .68 and 6.8% in the same NM-28 plant parts, respectively. Higher percentages of activity were recovered in palmer amaranth plant parts; 50.5% in treated leaf, 8.5% above treated leaf and 5.4% below.

A field demonstration was conducted in Mohave Valley to compare cotton morningglory control programs that combined the use of over the top herbicides Roundup Ultra on Roundup Ready cotton (Deltapine 436 RR) or Staple on non-transgenic cotton (SureGrow 125) with and without precision cultivation.

In the fall of 1999 an experiment was conducted to measure the effect of CGA- 362622, halosulfuron (Permit), glyphosate (Roundup Ultra) and Pyrithiobac (Staple) on purple nutsedge. Five rates of Permit (0.25, 0.375, 0.495, 0.75 and 1.0 oz a.i./A), three rates of CGA-362622 (3.035, 4.047, and 6.07 g a.i./A), and a single rate each of Roundup Ultra (0.75 lb a.e./A), Staple (1.5 oz a.i./A), Staple + Bueno 6 (2 lb a.i./A), and Staple + Fusilade (0.25 lb a.i./A) were applied either once or twice to field populations of purple nutsedge. Efficacy of each treatment was measured in three ways: phytotoxicity (stunting, chlorosis and/or necrosis) ratings were assigned to each plot (0 being no injury and 10 indicating death), the number of green leaves were counted on 3 large ($8 leaves) and 3 small (≤4 leaves) plants per plot at various times after treatment, and the amount of regrowth after the herbicide treatments was assessed. All of the herbicide treatments caused stunting, induced chlorosis and necrosis, and were fairly effective in controlling nutsedge plants treated at or before the 4-leaf growth stage. Only Permit and CGA-362622 effectively controlled plants treated at the 8-leaf growth stage after one application. The other four herbicides required two applications to obtain effective control. For the regrowth parameter parameters, Permit, CGA-362622 and Roundup Ultra effectively controlled regrowth, but the Staple, Staple + Bueno 6 and the Staple + Fusilade treatments did not control regrowth. Two applications of Permit at the .495 oz a.i./A or greater rates, Roundup Ultra (0.75 lb a.e./A) and 1 or 2 applications of the 6.070 g a.i./A rate of CGA-362622 controlled nutsedge with respect to all measured regrowth parameters and may be the best choices for controlling purple nutsedge.

Johnsongrass control with BAS 620 was 60% and 67% for the 0.124 and 0.248 lb ai/A rates respectively, 14 d after initial application. Control was comparable to Select at the corresponding rates. Control 28 d after the second application of graminicides ranged from 60% to 88%. Both rates of BAS 620 and Select as well as Fusilade DX provided the most effective control. Seed cotton yields ranged from 1347 to 3134 lbs/A and all herbicide treatments yielded significantly greater than the nontreated check.

Experiments were conducted at the University of Arizona Safford and Maricopa Agricultural Centers during the 2001 cotton season to compare the effectiveness of 0.5 and 1.0 lb a.i./A topical applications of Buctril (bromoxynil) on annual morningglory species. At Safford, the percent control of annual morningglory was statistically greater following 1.0 lb a.i./A Buctril applications at 97 percent control compared to 83 percent control resulting from 0.5 lb a.i./A Buctril applications. Both the 0.5 and 1.0 lb a.i./A Buctril rates, had similar initial effects on morningglory seedlings. Initial leaf symptoms included a dark-green “water soaked” appearance that progressed into leaf necrosis. At both rates, all morninglory leaf tissue was destroyed leaving green stems which sometimes remained viable and produced new leaves rather than turning chlorotic and dying. The number of escapes in the center two rows of four-row plots was significantly greater after 0.5 lb a.i./A Buctril applications at 12.4 escapes compared to 1.5 escapes following 1.0 lb a.i./A Buctril applications. An average of 12 escapes in an area 40 ft by two cotton rows is sufficient to cause substantial yield losses in the absence of other control methods. At Maricopa, there was no statistically significant difference in the phytotoxicity caused by 0.5 and 1.0 lb a.i./A Buctril rates when applied to 1, 2, or 3 true-leaf exposed morningglory seedlings (i.e., not partially covered or shaded by other plants) that were thoroughly contacted by the herbicide sprays. Both experiments found that morningglory control was significantly greater following two sequential 0.5 lb a.i./A Buctril applications compared to a single 1.0 lb a.i./A application due to continued emergence of seedlings. Growers with morningglory infested fields that make a 1.0 lb a.i./A application should be prepared to make an early season post-direct application using other herbicides to control later emerging morningglory plants.

Conservation or reduced tillage practices in cotton-based crop rotation systems were studied in field experiments initiated at Marana, Coolidge and Goodyear by planting barley cover and grain crops in the fall of 2001. In the 2002 cotton season, conservation tillage practices reduced the number of cultural operations required to grow a cotton crop. Adequate cotton weed control was achieved in conservation tillage systems using only postemergence herbicides; weedsensing, intermittent spray technology reduced the amount of herbicide spray volume used for weed control. Cotton yields in conservation tillage systems were similar to the yields in conventional tillage systems at two sites and greater at one site.