Weed overgrowth in high-value crops like onions remains a major challenge due to labor costs, herbicide resistance, and environmental concerns. Robotic laser-based weed control offers a precise, chemical-free alternative capable of targeting individual weeds while protecting crop health and the environment. This research introduces the application of a Clavel-based delta parallel robot for precision weed elimination using a high-power diode blue light laser. The delta robot employed in this study features three degrees of freedom and is capable of achieving maximum accelerations up to 20 m/s². It consists of aluminum proximal arms connected to servo motors and carbon fiber distal arms, reducing weight and enhancing agility. These servo motors are housed within a top base constructed from ABS 3D printed parts. Movement calculations and inverse kinematics are managed by an embedded ARM Cortex-M3 controller integrated with the servo motors. A 450 nm, 10W diode laser serves as the robot's end-effector, actuated using the Transistor-transistor logic (TTL) signals. Both robot movements and laser activation are simultaneously controlled through an external Arduino Mega 2560 microcontroller, leveraging a custom-developed C library to ensure workspace safety and precision. Experiments conducted to assess positional accuracy involved 100 trials, resulting in a mean radial positional error of 0.83 mm. Further experiments measured laser exposure time and stand-off distance. The results showed complete weed destruction in less than 6 seconds at distances of up to 100 mm. These results support the robot's effectiveness in targeted weed management for precision agriculture.
The use of pre-emergence herbicides under plastic mulch is an effective strategy for weed control in plasticulture beds in vegetable production systems. S-metolachlor is a pre-emergence herbicide labeled for application in soil prior to laying plastic mulch in tomato production in Florida. However, the risk of crop injury has limited its adoption in plasticulture systems, highlighting the need for crop-safe herbicide application approaches. This study aimed to evaluate the potential of herbicide safeners including chemical seed treatments and activated charcoal in mitigating tomato transplant injury from herbicides such as S-metolachlor. A greenhouse experiment was conducted at the Southwest Florida Research and Education Center (SWFREC) in Immokalee, FL, across two trials: March–June (Trial I) and August–November (Trial II) of 2024. Field soil was collected and used in pots for both trials. Treatments included tomato seed pre-treatments with benoxacor or fenclorim, and transplant root treatments with activated charcoal applied either as a root dip or poured into planting holes. All treated transplants and non-treated controls were grown in S-metolachlor-treated soil. Seed pre-treatment with benoxacor or fenclorim reduced crop injury by over 63% compared to non-treated controls. Activated charcoal applied to transplant roots reduced injury by 40–70% in Trial I and by over 70% in Trial II. Chlorophyll content was consistently higher in safener-treated plants, with activated charcoal increasing levels by more than 16% at 2 weeks after transplanting (WAT) and by 11–20% at 6-WAT. Similarly, benoxacor and fenclorim treatments improved chlorophyll content by 12–19% at 6-WAT. Root biomass in non-treated transplants was reduced by 56–70% due to S-metolachlor exposure. In contrast, both activated charcoal and seed-applied safeners helped preserve root biomass, with benoxacor and fenclorim reducing root weight loss by 65–70% compared to untreated controls. Overall, the results demonstrate that both seed-applied (benoxacor, fenclorim) and root-applied (activated charcoal) safeners are effective in mitigating S-metolachlor injury in tomato transplants and may offer viable strategies for enhancing crop safety in plasticulture-based vegetable production.
A successful Christmas tree production requires a good and effective weed management program. Most common weed control practices in Christmas tree production involve mechanical mowing and the application of chemical herbicides. Repeated applications of the existing herbicide options have resulted in the development of herbicide-resistant weed species. It is also important to test newer herbicides to expand the list of herbicide options. Hence the objectives of this research were to evaluate labeled (1X) and double (2X) rates of newer herbicides for weed control efficacy and for phytotoxicity in Fraser fir variety of Christmas tree. Field experiments were conducted in summer and fall 2024 at a commercial Christmas tree farm located at Gobles, MI. Christmas tree variety chosen for the experiment was four-year-old Fraser fir (Abies fraseri). The herbicide treatments included glyphosate trifloxysulfuron-sodium, glyphosate flumetsulam, glyphosate flumetsulam clopyralid, glyphosate chlorimuron, glyphosate cloransulam, glyphosate topramezone, glyphosate flumioxazin. Out of these treatments, the last two were considered as industry commercial standards. The control treatment included only glyphosate. All herbicides were tested for their labeled (1X) rates and double (2X) rates. Treatments were applied before bud break as directed application towards the lower 18 inches of the trees with a carbon dioxide backpack sprayer calibrated at 27 gallons per acre output. The experiments were complete randomized block design with four replications of each treatment. Data were collected at 1, 2, 3, and 4 months after treatment (MAT) which included visual estimation of weed control based on a scale of 0% to 100% (0% meaning no weed control and 100% meaning complete weed control) and phytotoxicity based on a scale of 0% to 100% (0% meaning no plant injury and 100% meaning complete death of a branch). Dominant weed species were recorded as well. Data were analyzed by ANOVA in SAS 9.4 and means were separated out by Tukey’s HSD test. Results showed that 1X rates of glyphosate chlorimuron and glyphosate trifloxysulfuron-sodium provided 70%-90% weed control till 4 MAT and their 2X rates showed no significant injuries to the Fraser fir variety till 4 months. Hence, glyphosate chlorimuron and glyphosate trifloxysulfuron-sodium can be additional options for Christmas tree growers for weed control in future. However, long-term multiple year studies are still required based on different herbicidal rates and on different varieties of Christmas trees for expansion of these herbicide labels.
Specialty and organic crop weed management strategies are challenging due to limited chemical control products with good efficacy that are cost effective. The need for new bioherbicide modes of action has become increasingly urgent in modern agriculture as most bioherbicides have nonspecific modes of action with no systemic activity. Introducing new bioherbicides that are also registered as organic is essential to diversify weed control strategies. By fostering innovations in bioherbicide development agricultural systems can be more environmentally friendly by preserving ecosystems while maintaining the ability to feed a growing global population. Manuka oil is derived from the leaves and branches of the Manuka tree (Leptospermum scoparium) and contains β-triketones. The β-triketone rich fraction contains leptospermone that inhibits a key enzyme, p-hydroxyphenylpyruvate dioxygenase (HPPD). This process directly inhibits carotenoid biosynthesis, upstream in the biochemical pathway, which causes damage to the photosynthetic apparatus and leads to bleaching of the leaf tissue which eventually kills the plant. There were three studies that examined the efficacy of β-triketone extract against Lolium multiflorum, Amaranthus retroflexus, and Abutilon theophrasti. The studies were 1) pre-emergence β-triketone extract ranging from 0 to 2.5 mg ml-1, 2) post-emergence β-triketone extract ranging from 0 to 6%, and 3) post-emergence β-triketone extract at 0.5 and 2.0% with five different organic adjuvants. In the pre-emergence study, there were significant differences between the β-triketone extract treatments and 100% weed control down to 0.625 mg ml-1. In the post-emergence study, there was significant decreases in weed height and fresh and dry mass when compared to the control treatment. However, the adjuvants did not have any effect on weed height and fresh and dry mass. Thus, there is significant evidence that commercializing a water soluble β-triketones enriched extract of Manuka oil can be an effective weed control, especially as a pre-emergent bioherbicide for specialty and organic crop production.
I am a Research Plant Physiologist with USDA-ARS in the Natural Product Utilization Research Unit in Oxford, MS. We are housed on the beautiful campus of the University of Mississippi. My research encompasses bioherbicide discovery from natural products and elucidating their modes... Read More →
A forum for discussion of potential collaborations with regards to plant growth and culture – i.e. propagation, root growth, water management, weed control, PGRs, plant nutrition, etc.
