Seventy-six Cucurbita pepo L. cultivars and breeding lines were evaluated under field conditions for infestation levels and defoliation (leaf area consumed by beetles) by adult diabroticite beetles in 1992 and 1994. Striped and spotted cucumber beetles, Acalymma vittatum (F.) and Diabrotica undecimpunctata howardi Barber, respectively, were most common, but some western and northern corn rootworms, D. virgifera virgifera LeConte and D. barberi Smith and Lawrence, respectively, also were present. In general, pumpkin, delicata, acorn winter squash, scallop, and yellow straightneck summer squash types were the least infested and defoliated. Caserta/yellow, zucchini, caserta/zucchini, caserta, and precocious yellow straightneck types were the most infested and defoliated. The number of beetles per plant was correlated (r ≥ 0.72) with leaf defoliation and proportion of plants infested, indicating that beetle infestation is a good predictor of damage. The cultivars and breeding lines that were the least infested and defoliated can be used in breeding programs to develop desirable genotypes with reduced beetle preference. Conversely, those genotypes that were highly preferred have potential as trap crops for these beetle pests.
Michael P. Hoffmann, Richard W. Robinson, Margaret M. Kyle and Jonathan J. Kirkwyland
Zachary D. Small, James D. McCurdy, Erick D. Begitschke and Michael P. Richard
Wild garlic (Allium vineale) is an annual winter weed in managed turfgrass. Its dark green, upright stems are easily distinguishable among low-lying, dormant warm-season grasses. Experiments were conducted to determine the effectiveness of synthetic auxin and acetolactate synthase (ALS) inhibiting herbicides for post-emergence control of wild garlic. Trials were conducted in 2016 and 2017. Throughout both trial years, synthetic auxin herbicides exhibited visual control quicker than ALS inhibitors at the initial assessment date 20 d after application (DAA). Conversely, at the final assessment date 49 DAA, ALS inhibitors were the only treatments that controlled wild garlic by more than 85%. In 2016, plots treated with 2,4-D + dicamba + mecoprop at 4 pt/acre exhibited 88% visual control when assessed 20 DAA, but this level had decreased to 51% by 49 DAA. Similarly, visual control in plots treated with 2,4-D + mecoprop + dicamba + carfentrazone-ethyl at 4 pt/acre decreased from 59% to 56% and 82% to 18% between assessment dates in 2016 and 2017, respectively. Metsulfuron-methyl at 0.5 fl oz/acre controlled wild garlic 94% and 91% at the 49 DAA assessment date, whereas sulfentrazone + metsulfuron-methyl at 0.41 lb/acre controlled wild garlic 93% and 95% at the same assessment dates in 2016 and 2017, respectively. Future research should consider tank mixes of auxin-mimicking and ALS-inhibiting herbicides as potential routes for quick burndown and season-long control.
Andrew P. Pond, James L. Walworth, Michael W. Kilby, Richard D. Gibson, Robert E. Call and Humberto Núñez
Measurement of nutrients in leaf tissue is a practical method of monitoring the nutritional status of perennial crops such as pecan (Carya illinoinensis, Wang. C. Koch). Accurate interpretations require known standard concentrations for the crop and region. To determine standard concentrations for pecans, focusing on those grown in the desert southwest, we conducted a survey of 135 `Western Schley' pecan trees in Arizona for 2 years. Leaf nutrient concentrations and yield were collected for each tree. Leaf nutrient concentrations from the highest yielding trees (50th yield percentile) were used to calculate a mean and CV for each nutrient. Results were compared with data from New Mexico, Georgia, and Sonora, Mexico. Relatively large differences were noted in mean K, Ca, B, Cu, Fe, Mn, and Zn levels. Nutrient interpretation ranges were calculated based on Arizona population statistics using the balance index method.
Erick G. Begitschke, James D. McCurdy, Te-Ming Tseng, T. Casey Barickman, Barry R. Stewart, Christian M. Baldwin, Michael P. Richard and Maria Tomaso-Peterson
Preemergence herbicides generally have a negative effect on hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] establishment. However, little is known about the effect they have on root architecture and development. Research was conducted to determine the effects of commonly used preemergence herbicides on ‘Latitude 36’ hybrid bermudagrass root architecture and establishment. The experiment was conducted in a climate-controlled greenhouse maintained at 26 °C day/night temperature at Mississippi State University in Starkville, MS, from Apr. 2016 to June 2016 and repeated from July 2016 to Sept. 2016. Hybrid bermudagrass plugs (31.6 cm2) were planted in 126-cm2 pots (1120 cm3) and preemergence herbicide treatments were applied 1 d after planting at the recommended labeled rate for each herbicide. Preemergence herbicide treatments included atrazine, atrazine + S-metolachlor, dithiopyr, flumioxazin, indaziflam, liquid and granular applied oxadiazon, S-metolachlor, pendimethalin, prodiamine, and simazine. Treatments were arranged in a completely randomized design with four replications. Plugs treated with indaziflam and liquid applied oxadiazon failed to achieve 50% hybrid bermudagrass cover by the end of the experiment. Of the remaining herbicide treatments, all herbicides other than granular applied oxadiazon and atrazine increased the number of days required to reach 50% cover (Days50). In addition, all herbicide treatments reduced root mass when harvested 6 weeks after treatment (WAT) relative to the nontreated. By 10 WAT, all treatments reduced root mass in run 1, but during run 2, only prodiamine, pendimethalin, simazine, atrazine + S-metolachlor, liquid applied oxadiazon, and indaziflam reduced dry root mass compared with the nontreated. At 4 WAT, all treatments other than simazine and granular applied oxadiazon reduced root length when compared with the nontreated. By 10 WAT, only dithiopyr, S-metolachlor alone, and indaziflam reduced root length when compared with the nontreated. No differences were detected in the total amounts of nonstarch nonstructural carbohydrates (TNSC) within the roots in either run of the experiment. Results suggest that indaziflam, dithiopyr, and S-metolachlor are not safe on newly established hybrid bermudagrass and should be avoided during establishment. For all other treatments, hybrid bermudagrass roots were able to recover from initial herbicidal injury by 10 WAT; however, future research should evaluate tensile strength of treated sod.
Emily E. Hoover, Richard P. Marini, Emily Tepe, Wesley R. Autio, Alan R. Biggs, Jon M. Clements, Robert M. Crassweller, Daniel D. Foster, Melanie J. Foster, Peter M. Hirst, Diane Doud Miller, Michael L. Parker, Gregory M. Peck, Jozsef Racsko, Terence L. Robinson and Michele R. Warmund
Researchers have collected a considerable amount of data relating to apple (Malus ×domestica) cultivars and rootstocks over the past 30 years, but much of this information is not easily accessible. The long-term goal of our working group is to increase access to this information using online technology available through eXtension. In eXtension, researchers and extension personnel are developing a community of practice (CoP) to increase the quality and amount of online information for individuals interested in our work [referred to as a community of interest (CoI)]. For this project, our CoI is broadly defined as commercial apple producers, nursery professionals, county extension educators, Extension Master Gardeners, home gardeners, and consumers. Our CoP is developing diverse educational tools, with the goals of increasing productivity, profitability, and sustainability for commercial apple production. Additionally, we will provide other members of our CoI access to research-based, reliable information on the culture of apples. We chose to begin our focus on cultivars and rootstocks adapted to the eastern United States and will add other U.S. regions as our resources and interest in our project grows.