Implementation Of Cultural Practices Research Articles

Suppression of Hop Downy Mildew as Influenced by the Timing of Selected Fungicides

Downy mildew of hop is a disease that is controlled by the implementation of cultural practices along with the application of fungicides, as there are few cultivars with high levels of resistance to this disease. We conducted studies in western Oregon to elucidate the effect of using synthetic fungicides of various modes of action early versus late in disease management programs when rotated with a copper-based fungicide. When analyzed over the 4 years of this study, there were independent effects from both the specific fungicide mode of action and application timing on disease control. The use of cymoxanil + copper hydroxide or mandipropamid in a program reduced the area under the disease progress curve by 66.3 or 59.7 units (17.7 or 19.6%), respectively, as compared with phosphorous acid. Using synthetic fungicides in the first two applications in a program provided better disease control than using the same fungicides in the third and fourth applications, reducing the area under the disease progress curve by 47.8 units (14.4%). By simply applying modes of action found to be more efficacious earlier in the growing season, the severity of downy mildew was reduced as much as 32% without increasing the total number of applications made.

Papaya Mealybug in Kenya: Identification, Management, and Future Outlook

Abstract Papaya mealybug, Paracoccus marginatus is the most important and damaging insect pest species attacking papaya in Kenya. In addition, it feeds on various crops, fruits, and ornamental plants, most of which are of high economic value in Kenya’s agricultural sector such as chilli pepper, mango, citrus, cassava, avocado, and coffee. The mealybugs cause damage by inserting their stylets into fruits, leaves, and stems, directly feeding on the plant’s vascular system and depleting the sap. Consequently, this leads to chlorosis, plant stunting, leaf deformation, and, if left uncontrolled, leads to eventual plant death. The control of papaya mealybug on Kenyan farms has primarily depended on the application of chemical pesticides and the implementation of cultural practices, but the effectiveness of these methods has been widely reported as inadequate and burdensome. Biological control using a parasitoid Acerophagus papayae offers an alternative and sustainable option for the management of papaya mealybug and simultaneously safeguards the native biodiversity threatened by excessive pesticide use. This case study provides insights into the identification, distribution, impacts, and existing management strategies of papaya mealybug in Kenya. Additionally, it emphasizes ongoing and future research endeavours aimed at enhancing papaya mealybug management techniques. Information © The Authors 2023

A Genome Resource for Several North American Venturia inaequalis Isolates with Multiple Fungicide Resistance Phenotypes.

The apple scab pathogen, Venturia inaequalis, is among the most economically important fungal pathogens that affects apples. Fungicide applications are an essential part of disease management. Implementation of cultural practices and genetic sources of resistance in the host are vital components of scab management. This is the first presentation of multiple, high quality, well-annotated genomes of four North American V. inaequalis isolates having both sensitive and multiple fungicide resistance phenotypes. We envision that these isolates will enable investigations into fungicide resistance mechanisms, exploring fungal virulence factors and delineating phylogenomic relationships among apple scab isolates from around the world.

Bacterial Wilt of Dry-Edible Beans in the Central High Plains of the U.S.: Past, Present, and Future.

Bacterial wilt, caused by Curtobacterium flaccumfaciens pv. flaccumfaciens, was first recognized and described as a new dry bean disease near Redfield, SD after the 1921 growing season on the farm of the Office of Forage Investigations. Between the late 1930s and the early 1950s it became one of the more problematic bacterial diseases of dry beans. It became an endemic problem in dry bean production throughout western Nebraska and other areas of the central high plains during the 1960s and early 1970s. By the early 1980s, the disease had virtually disappeared with the implementation of cultural practices. The disease was rediscovered in two fields in Nebraska late in the 2003 season. It was assumed to be an isolated incident. However, the next season the pathogen was widespread throughout western Nebraska production fields. Our research suggests that the return of bean wilt throughout the central high plains over the last decade is not due to a single factor but a combination of new changes in cultural practices, environmental stresses, and unfamiliarity with the pathogen and its past history.

Application of thiophanate-methyl at different host growth stages for management of sclerotinia stem rot in soybean

Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum, is an important disease of soybean ( Glycine max L.) in the North Central United States. The incidence of SSR can be reduced by planting partially resistant cultivars and by implementation of cultural practices that limit pathogen activity. Fungicides such as thiophanate-methyl are another option for control of SSR, but usually recommended in situations where susceptible cultivars must be grown or modification of cultural practices are not disease control options. Previous studies have shown that control of SSR with fungicides is possible, but that the degree of control is inconsistent especially when incidence of SSR surpasses 50%. This study was designed to evaluate the efficacy of single or multiple applications of thiophanate-methyl in relation to timing of inoculation and early reproductive growth stages of the host. Inoculum was introduced at growth stage R2 at the Illinois location, and naturally occurring inoculum was relied upon to initiate SSR at the Wisconsin location. Thiophanate-methyl was effective when applied at R1 prior to inoculation at R2, but not if applied at R3, after inoculation. Two applications of thiophanate-methyl starting at R1 or the R2 growth stage and a second 2 weeks later lowered the incidence of SSR at the naturally infested Wisconsin site compared to one application with one exception. The incidence of SSR was identical for one and two applications starting at R1.5. Soybean yield was improved by fungicides at both experimental locations, and coincided with timing, and number of applications. Data from both locations suggested that fungicides need to be applied prior to inoculum arrival to the infection court. One application was effective in the controlled inoculation study, but two applications were needed at the naturally infested location. Two applications of thiophanate-methyl improved yield of a partially resistant soybean cultivar even though the incidence of SSR was <10% at the Wisconsin location. Thiophanate-methyl is an effective option for control of SSR, especially to reduce seedborne inoculum in commercial seed production systems.