The windmill palm is a distinctive outdoor ornamental palm adapted to cooler climates. Weeds pose significant challenges in palm nurseries, particularly during seedling and establishment stages. This research was conducted in a nursery with 5,500 windmill palm seedlings, starting in April 2014, when the palm trees were 3 yr old. Experiments were terminated in October 2018 when weed control was no longer necessary due to the advanced growth of the palm trees. The objectives of this study were to determine the weed composition and diversity, elucidate the effects of mechanical weed management (MWM) on growth rate of palm, and develop a sustainable program to maximize palm tree growth through effective weed management and soil tillage. Few herbicides are registered for nursery use in Türkiye, thus weed control was performed mechanically using garden hoeing machines between rows and hand hoeing for intrarow strips. The most common and dense weeds were purple nutsedge, annual mercury, and common purslane in summer and autumn, and burning nettle in winter and spring. In 2014, weed densities were 100, 127, and 145 weeds m–2 for MWM, hand-weeding (HW), and nontreated (NT) plots, respectively. Transplanted palm seedlings required at least two, ideally three growing seasons of intensive weed control until the palm tree crowns block sunlight and suppress weed growth. The research indicated that palm trees in the MWM treatment had approximately 84 leaves and a height of 210 cm by October 2018, compared with 54 leaves and a height of 136 cm for HW, and 40 leaves and 100 cm height for NT. These results highlight the critical role of MWM in promoting optimal growth of Chinese windmill palms. Effective and sustainable weed management, combining MWM and HW, is essential for producing high-quality palm trees. The research provides valuable insights for nursery managers and contributes to best practices for cultivating windmill palm trees in similar climatic regions.

Sulfuryl fluoride (SF) is currently used as a fumigant for control of drywood termites and insects in building structures, vehicles, wood products, postharvest commodities, and food processing facilities. This research investigated the feasibility of using SF as a preplant soil fumigant for purple nutsedge control in plastic-mulched tomato production. SF treatments included SF injected through drip tapes or SF injected through drip tapes a few hours following shank injection of chloropicrin (Pic). Results revealed that SF alone at 224, 336, or 448 kg ha−1 was generally less effective compared with when it was applied in conjunction with Pic at 168 kg ha−1. SF alone provided inconsistent control of purple nutsedge. In contrast, SF + Pic was as efficacious or more efficacious on purple nutsedge than the industry standards, including 1,3-dichloropropene (1,3-D) plus Pic and metam potassium. None of the fumigant treatments visually injured tomato plants, stunted growth, or adversely affected tomato yield. In one of the four tomato seasons, tomato plants growing in plots fumigated with SF + Pic resulted in taller tomato plants and higher markable yields. Results indicate that soil fumigation with SF + Pic is safe on plastic-mulched tomato and effectively controls purple nutsedge.

Metam potassium (metam-K) is a soil fumigant used commonly in Florida at the end of the tomato and pepper production season. The fumigant essentially cleans a field by killing the established weeds and crops after harvest. The goal of this project was to determine the optimal rate of metam-K for the effective termination of tomato, pepper, and established weeds such as purple nutsedge, goosegrass, and dogfennel. Tomato, pepper, and purple nutsedge at bed center were effectively terminated with the metam-K rate of 65 kg ha−1. Optimal rates required for the termination of goosegrass and dogfennel were 91 and 156 kg ha−1, respectively. In contrast, metam-K at 500 to 680 kg ha−1 was required to terminate purple nutsedge on bed edges. The reduced efficacy of metam-K at bed edge might be related to the limited movement of metam-K in soil.

Greenhouse experiments were conducted to determine the extent of purple nutsedge tuber depletion and shoot regrowth when shoots were removed periodically from plants sprouting from tubers of different original weights. Presprouted purple nutsedge tubers were planted in 0.5-L plastic containers filled with potting medium. Tuber weight categories were 0.25, 0.50, 0.75, and 1 g per tuber. Shoots were removed by cutting at soil level beginning 6, 12, 18, 24, or 30 d after transplanting (DAT). Shoot removal occurred every 6 d after the first removal with a minimum of seven removals. Tuber weight had an effect on both shoot number and dry weight when the first removal was imposed either 6 or 12 DAT. When initial shoot removal was begun 6 DAT, total tuber depletion was achieved after the fifth removal for tubers weighing 0.25 g and after the seventh removal for tubers weighing 0.50 g. When the initial removal was delayed until 12 DAT, only tubers weighing 0.25 g were depleted after the sixth removal. No tuber depletion occurred for tubers weighing 0.75 g or more at any initial removal time. Greater initial sprouting vigor was observed among large tubers compared to smaller ones. Early removal (6 DAT) promoted the formation of more shoots from tubers weighing 0.75 or 1 g.

Experiments were conducted from 1988 through 1991 to evaluate the effectiveness of imazethapyr alone and in combination with metolachlor for control of yellow and purple nutsedge. Imazethapyr alone at 0.07 kg ha–1 controlled yellow nutsedge irregularly while the addition of metolachlor greatly improved control. Metolachlor preplant incorporated (PPI) followed by imazethapyr at ground-crack (GC) or postemergence (POST) controlled 72 to 96% of yellow nutsedge, whereas a tank-mix of metolachlor plus imazethapyr PPI controlled 85 to 96%. The addition of metolachlor to imazethapyr did not result in any improvement in control of purple nutsedge. Metolachlor plus imazethapyr PPI controlled ≥ 85% of purple nutsedge PPI, whereas imazethapyr POST controlled ≥ 94%.

The allelopathic influence of sweet potato cultivar ‘Regal’ on purple nutsedge was compared to the influence on yellow nutsedge under controlled conditions. Purple nutsedge shoot dry weight, total shoot length and tuber numbers were significantly lower than the controls (47, 36, and 19% inhibition, respectively). The influence on the same parameters for yellow nutsedge (35, 21, and 43% inhibition, respectively) were not significantly different from purple nutsedge. Sweet potato shoot dry weight was inhibited by purple and yellow nutsedge by 42% and 45%, respectively. The major allelopathic substance from ‘Regal’ root periderm tissue was isolated and tested in vitro on the two sedges. The I50's for shoot growth, root number, and root length were 118, 62, and 44 μg/ml, respectively, for yellow nutsedge. The I50's for root number and root length were 91 and 85 μg/ml, respectively, for purple nutsedge and the I50 for shoot growth could not be calculated.

Genetic diversity within and among populations of yellow nutsedge (Cyperus esculentus L. # CYPES) was analyzed to evaluate and quantify the genetic consequences of the reported predominance of asexually-produced tubers as colonizing agents. Ten populations were examined using starch gel electrophoresis for allozyme analysis. Four populations of purple nutsedge (Cyperus rotundus L. # CYPRO) were surveyed for comparison. Twelve loci were identified in yellow nutsedge among the eight enzyme systems examined; ten of these loci were found in purple nutsedge. Yellow nutsedge showed relatively low genetic diversity. Most of the genetic diversity occurred as differences among individuals within populations (Hs), compared to differences among populations (Dst) for the four variable loci identified in this species. Thus, most genetic distances between its populations were small. Generally, only a few genotypes occurred within each population. Purple nutsedge was found to possess even lower within- and among-population gene and genotypic diversity. This study supports the view that tubers account for most of the establishment of new populations of both species.

An isolate of the fungus Dactylaria higginsii obtained from purple nutsedge in Florida was highly pathogenic to Cyperus spp. The potential of this isolate as a bioherbicide was field tested in natural populations of purple nutsedge in Gainesville and Jay, FL. The fungus was applied in 0.5% Metamucil® as a carrier, and the treatments were: carrier only, 105 conidia/ml + carrier, and 106 conidia/ml + carrier. Treatments were applied as single, double, or triple postemergence (POST) sprays at biweekly intervals. The disease and secondary infections developed in about 5 and 15 d after inoculation, respectively, killing most of the infected leaves. All weed growth parameters and disease progress rates were affected by inoculum dosage and inoculation frequencies. Three inoculations, each at 106 conidia/ml, provided effective control of purple nutsedge compared to a single inoculation, as measured by shoot dry weight, tuber numbers, and tuber dry weight. Higher rates of disease progress and disease levels, defined by the area under the disease progress curve (AUDPC), occurred with three inoculations at 106 conidia/ml. Disease progress was slower and the level of weed control was lower at 105 conidia/ml compared to the higher inoculum level. Three applications of 106 conidia/ml provided >90% nutsedge control. Dactylaria higginsii appears to be an effective bioherbicide candidate deserving further development for commercial use.

Soil solarization has been proposed as an alternative to methyl bromide for controlling nutsedges. Little is known, however, about the relationship between soil solarization and nutsedge tuber viability. Combinations of elevated temperatures and durations of exposure were evaluated for their effect on purple nutsedge and yellow nutsedge tuber viability and new tuber production in growth chamber studies. Estimates of the duration of exposure at each temperature that reduced nutsedge growth parameters 50% (TT50) were supplied by log-logistic regression analysis. Nutsedge tuber viability was reduced when temperatures were ≥ 45 C. Relative to purple nutsedge, yellow nutsedge tuber viability had smaller TT50 values for 45, 50, and 55 C. Tuber viability TT50 at 60 C was similar for both nutsedges. The TT50 for production of new purple nutsedge tubers at 50 C was larger than that for yellow nutsedge. However, there were no differences between species in TT50 values for new tuber production at higher temperatures. With sufficient durations of exposure, both purple and yellow nutsedge tubers were killed at temperatures ≥ 50 C. However, application of these data to field situations in Georgia may be limited using present technology because the soil temperature cannot be raised to high enough levels for acceptable solarization effects.

Leaf-cover area is a widely required plant development parameter for predictive models of weed growth and competition. Its assessment is performed either manually, which is labor intensive, or via visual inspection, which provides biased results. In contrast, digital image processing enables a high level of automation, thereby offering an attractive means for estimating vegetative leaf-cover area. Nonetheless, image-driven analysis is greatly affected by illumination conditions and camera position at the time of imaging and therefore may introduce bias into the analysis. Addressing both of these factors, this paper proposes an image-based model for leaf-cover area and biomass measurements. The proposed model transforms color images into an illumination-invariant representation, thus facilitating accurate leaf-cover detection under varying light conditions. To eliminate the need for fixed camera position, images are transformed into an object–space reference frame, enabling measurement in absolute metric units. Application of the proposed model shows stability in leaf-cover detection and measurement irrespective of camera position and external illumination conditions. When tested on purple nutsedge, one of the world's most troublesome weeds, a linear relation between measured leaf-cover area and plant biomass was obtained regardless of plant developmental stage. Data on the expansion of purple nutsedge leaf-cover area is essential for modeling its spatial growth. The proposed model offers the possibility of acquiring reliable and accurate biological data from digital images without extensive photogrammetric or image-processing expertise.

Greenhouse studies were conducted to evaluate halosulfuron tolerance of several squash and cucumber cultivars commonly grown in Georgia. There was an inverse linear relationship between squash plant biomass and rate of halosulfuron (r 2 = 0.70 to 0.92). With the exception of ‘Supersett’, the slopes from regression of all squash cultivars were equivalent. The estimated amount of halosulfuron required to reduce growth by 20%, based on regression, ranged from 8.2 to 45 g ai/ha (for Supersett and ‘Dixie’, respectively). Squash plant height was also reduced by halosulfuron, though plants began to recover from the injury by the end of the study. There was no effect of halosulfuron rate on cucumber plant biomass or height. Cucumber cultivars appeared to be more tolerant to halosulfuron than did squash cultivars.

The looming water crisis and shortage of labor during rice transplanting in northwest India have led researchers to develop alternative methods to transition away from puddled transplanted rice. In this context, dry-seeded rice (DSR) is emerging as an efficient production technology to replace puddled transplanted rice. Weeds, however, are the main biological constraints to its success. A study comprising 12 treatments was conducted to evaluate the efficacy of PRE (pendimethalin and pyrazosulfuron) and POST herbicides (bispyribac, penoxsulam, and azimsulfuron) applied either alone or in a sequence for weed control in dry-seeded fine rice cv. ‘Punjab Mehak 1’. Results indicated that the single application of pendimethalin (750 g ai ha−1) PRE, pyrazosulfuron (15 g ai ha−1) PRE, bispyribac-sodium (25 g ai ha−1) POST, penoxsulam (25 g ai ha−1) POST, and azimsulfuron (20 g ai ha−1) POST reduced total weed biomass by 75, 68, 73, 70, and 72%, respectively, compared with the nontreated control at flowering stage of the crop. Azimsulfuron POST and pyrazosulfuron PRE proved effective against purple nutsedge and crowfootgrass, respectively. Chinese sprangletop, large crabgrass, and junglerice were effectively controlled with pendimethalin PRE. POST application of bispyribac-sodium and penoxsulam provided effective control of rice flatsedge. Compared to the nontreated control, grain yield following the single application of pendimethalin PRE, pyrazosulfuron PRE, bispyribac-sodium POST, penoxsulam POST, and azimsulfuron POST increased by 149, 119, 138, 124, and 144%, respectively. The sequential application of herbicides proved better than single applications. The lowest weed biomass was observed with the sequential application of pendimethalin PRE followed by azimsulfuron POST, and rice yielded 228% more than the nontreated control following this treatment. The results of this study are important for farmers growing DSR in making decisions regarding the application of POST herbicides, according to existing weed flora in the field.