Agrochemicals

17 pages, 511 KiB

Open AccessEditor’s ChoiceArticle

Toxicity Assessment of 36 Herbicides to Green Algae: Effects of Mode of Action and Chemical Family

by Simeng Li and Hailey Mcintyre

Agrochemicals 2024, 3(2), 164-180; https://doi.org/10.3390/agrochemicals3020012 - 22 May 2024

Viewed by 1796

Aquatic ecosystems can suffer inadvertent contamination from widely used herbicides. This study delves into the relative toxicity of 36 herbicides on green algae, exploring 11 distinct modes of action and 25 chemical structure classes. Through a 72-h algal growth inhibition test, it was found that herbicides targeting acetolactate synthase (ALS), photosystem II (PSII inhibitors), microtubule assembly, very-long-chain fatty acid (VLCFA) synthesis, and lipid synthesis exhibited high toxicity, with 72-h EC50 (half-maximal effective concentration) values ranging from 0.003 mg/L to 24.6 mg/L. Other pesticide types showed moderate to low toxicity, with EC50 values ranging from 0.59 mg/L to 143 mg/L. Interestingly, herbicides sharing the same mode of action but differing in chemical composition displayed significantly varied toxicity. For instance, penoxsulam and pyribenzoxim, both ALS inhibitors, demonstrated distinct toxicity levels. Similarly, terbuthylazine and bentazone, both PSII inhibitors, also exhibited differing toxicities. Notably, herbicides approved for rice cultivation showed lower toxicity to green algae compared to those intended for terrestrial plants. These data offer valuable insights for assessing the potential risks posed by these chemicals to aquatic organisms. Additionally, to prevent or minimize herbicide residual effects, modern management practices were reviewed to offer practical guidance. Full article

(This article belongs to the Section Herbicides)

► Show Figures

Figure 1

17 pages, 22262 KiB

Open AccessCase Report

Achievements and Challenges in Controlling Coffee Leaf Rust (Hemileia vastatrix) in Hawaii

by Luis F. Aristizábal

Agrochemicals 2024, 3(2), 147-163; https://doi.org/10.3390/agrochemicals3020011 - 31 Mar 2024

Cited by 1 | Viewed by 1888

Abstract

In this case study, the current situation faced by coffee growers attempting to control coffee leaf rust (Hemileia vastatrix) in Hawaii is reported. CLR is considered the most devastating disease affecting coffee crops worldwide and was detected in Hawaii in 2020. Three small coffee farms from the South Kona district of Hawaii Island were selected. The goals of this case study were to: (1) assist coffee growers in the early detection of CLR incidence, and consequently support farmers with recommendations for control, (2) record agronomic information and management practices, and (3) estimate the cost to control CLR during 2021 and 2022 seasons. Low CLR incidence (<4%) was initially observed at all farms (January–June 2021), but increased as the harvest began, ending the season (December 2021) at 77%, 21% and 6% incidence at farms 1, 2 and 3, respectively. At the end of 2022 season (December), CLR incidence reached 43%, 20% and 3% at farms 1, 2 and 3, respectively. The number of sprays per season (5–10), the type of fungicides applied (preventive, curative), the timing of sprays, the efficacy of applications and weather conditions all played a role in determining the infection rates at each farm. Effective control of CLR is possible in Hawaii if the sprays of fungicides are carried out with the right products, appropriate timing and good coverage. Full article

(This article belongs to the Section Fungicides and Bactericides)

► Show Figures

Figure 1

29 pages, 910 KiB

Open AccessEditor’s ChoiceReview

Integrating Biological Control Agents for Enhanced Management of Apple Scab (Venturia inaequalis): Insights, Risks, Challenges, and Prospects

by Chisom Augusta Okoro, Abbas El-Hasan and Ralf T. Voegele

Agrochemicals 2024, 3(2), 118-146; https://doi.org/10.3390/agrochemicals3020010 - 25 Mar 2024

Viewed by 2323

Abstract

Apple scab incited by the ascomycete Venturia inaequalis poses a significant threat to apple cultivation, necessitating a reassessment of existing disease management strategies. Attempts to manage apple scab include diverse approaches like developing disease forecasting models and the extensive application of synthetic chemical fungicides. However, the efficacy of these methods is compromised by inconsistencies, environmental concerns, and the pathogen’s resistance, necessitating the exploration of alternative sustainable strategies. Addressing the challenges associated with apple scab management, this review strongly supports a shift towards the integration of biological control agents (BCAs). Emphasising the transformative synergy between BCAs and their bioactive secondary metabolites, we highlight their efficacy in advancing precision disease control through innovative and sustainable solutions. The review effectively presents a strong justification for the integration of BCAs and their by-products into apple scab management, offering insights into associated benefits, risks, and challenges while outlining promising prospects. Ultimately, it is expected to drive the adoption of environmentally conscious practices for effective apple scab management. Full article

(This article belongs to the Special Issue Feature Papers on Agrochemicals)

► Show Figures

Figure 1

11 pages, 1454 KiB

Open AccessArticle

Air Assistance and Electrostatic Spraying in Soybean Crops

by Mariana Rodrigues Bueno, Guilherme Sousa Alves, Sérgio Macedo Silva, Tiago Seiji S. Hachiya, Hasle Thiago S. Guimarães, Gustavo Araújo Costa, Felipe Soares Gonçalves and Mateus A. V. G. Oliveira

Agrochemicals 2024, 3(2), 107-117; https://doi.org/10.3390/agrochemicals3020009 - 24 Mar 2024

Viewed by 1185

Abstract

This study aimed to evaluate the efficiency of air assistance associated with electrostatic spraying in terms of spray deposition and yield (Experiment 1), and the coverage and droplet density on soybean crops at different working speeds (Experiment 2). The treatments in Experiment 1 corresponded to combinations of electrostatic systems associated with air assistance at three airspeeds (21, 25, and 30 m·s⁻¹) plus a conventional treatment without electrostatic or air assistance. The treatments in Experiment 2 corresponded to three working speeds (3.3, 4.2, and 5.0 m·s⁻¹) with or without the use of an electrostatic system. All applications were performed with a self-propelled sprayer, delivering 75 L·ha⁻¹ with ATR 2.0 nozzles. A blue tracer, detectable as absorbance with a spectrophotometer, was added to the spray solution to evaluate deposition. The results indicate that an air assistance at 21 m·s⁻¹ plus electrostatic system increased the amount of spray deposited on the middle and top leaves of the plants in relation to the conventional system, with yield increments of up to 621 kg·ha⁻¹. The slowest working speed (3.3 m·s⁻¹) combined with air assistance and an electrostatic system provided the greatest spray deposition, droplet coverage, and density on the bottom leaves of soybean crops. Full article

► Show Figures

Figure 1

Journal Menu

Journal Browser

Agrochemicals, Volume 3, Issue 2 (June 2024) – 4 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI