Old but Gold: Captan Is a Valuable Tool for Managing Anthracnose and Botrytis Fruit Rots and Improving Strawberry Yields Based on a Meta-Analysis.

Botrytis fruit rot (BFR) and anthracnose fruit rot (AFR) are diseases of concern to strawberry growers. Both diseases are managed mainly by fungicide applications from the nursery (plant production) to the end of the growing season (fruit production). In Florida, captan is the main broad-spectrum fungicide used to control BFR and AFR. It has been tested in many trials over the years in various programs in alternation with single-site fungicides or weekly applications. Due to its broad-spectrum activity, captan is a pivotal tool in fungicide resistance management, because resistance to several fungicides has been reported in populations causing BFR and AFR. Our objective was to determine the effectiveness and profitability of applications of captan for controlling BFR and AFR based on a univariate meta-analysis considering data from 25 field trials conducted from 2005 to 2021 in Florida. Captan applications significantly improved marketable yields and reduced BFR and AFR incidence during late- and total-season periods. Marketable yields were significantly improved even when the effect on disease control was not significant. Our results indicate 100% probability that weekly captan applications would return the investment during low, medium, and high strawberry pricing regimes, although the magnitude of the return will depend on strawberry market prices. However, the probabilities of reducing BFR, AFR, and culls were lower. Results from our meta-analysis demonstrate the value of captan as an important tool for strawberry growers. Captan applications, in addition to effectively controlling BFR and AFR and improving marketable yields, will result in investment returns at any strawberry price level.

Validation of a Decision Support System for Blueberry Anthracnose and Fungicide Sensitivity of Colletotrichum gloeosporioides Isolates.

Blueberry is an increasingly important crop in Florida. Anthracnose fruit rot (AFR), caused mostly by Colletotrichum gloeosporioides, is favored by long wetness periods and temperatures from 15 to 27°C. Currently, the model in the Strawberry Advisory System (StAS) guides fungicide applications targeting strawberry AFR. Given the similarity between blueberry and strawberry AFR, we hypothesized that the model used in StAS could be used in a decision support system (DSS) built for blueberry AFR. There is no information on inhibition posed by fungicides on C. gloeosporioides isolates from blueberry. Our objectives were to demonstrate that the model used in the StAS could be used for blueberry AFR management in Florida and to assess the sensitivity of isolates to fungicides. Four trials were undertaken in blueberry fields in Florida during two seasons to compare the effectiveness of fungicide applications according to the model with that of the growers' standard calendar. Sensitivity of blueberry C. gloeosporioides isolates to azoxystrobin, benzovindiflupyr, penthiopyrad, pydiflumetofen, boscalid, thiophanate-methyl, fluazinam, and fludioxonil was evaluated. AFR incidence and yield were compared between treatments. Following recommendations from the model resulted in disease control as effective as the standard program and in some cases with fewer applications. All isolates were sensitive to benzovindiflupyr, penthiopyrad, fluazinam, and fludioxonil. Low frequency of in vitro inhibition of isolates by azoxystrobin, pydiflumetofen, boscalid, and thiophanate-methyl should raise concern about fungicide resistance. Our results indicate that the model used in StAS could be used in a DSS to help Florida growers to manage AFR in blueberry.

Cultivar Selection Is an Effective and Economic Strategy for Managing Charcoal Rot of Strawberry in Florida.

Macrophomina phaseolina, the causal agent of charcoal rot, is a soilborne pathogen that affects strawberry crowns leading to plant wilt and collapse. Disease management involves a combination of physical, cultural, and chemical methods. Field trials were conducted for 10 consecutive Florida seasons (2010-11 to 2019-20) to determine the susceptibility of strawberry cultivars to charcoal rot and the effect of cultivar selection on disease and to estimate the economic impact of cultivar selection on disease management. Six cultivars grown commercially in Florida were chosen and grouped as highly susceptible (HS) ('Strawberry Festival' and 'Treasure'), susceptible (S) ('Florida Radiance' and 'Florida Beauty'), and moderately resistant (MR) (Sensation 'Florida127' and Winterstar 'FL05-107') according to their susceptibility levels. After a primary analysis of the individual trials, a network meta-analysis was conducted to estimate and compare the final disease incidence and the disease progress rate of each susceptibility group. The economic impact of charcoal rot on strawberry production and gross revenue was estimated based on plant production functions, weekly fruit prices, and disease progress over time with parameters obtained via the meta-analytical models. Disease incidence was reduced by 91.5 and 77.3%, respectively, when the MR and S cultivar groups were adopted instead of the HS group. There was a 62.5% reduction in the disease incidence when the MR group was used instead of the S group. Significant differences in disease progress rates were also observed when the MR and S groups were adopted instead of the HS group. Therefore, the adoption of more resistant cultivars is an effective strategy when incorporated into a charcoal rot integrated management program and can significantly impact growers' revenue by reducing disease incidence, preventing yield loss, and, consequently, minimizing economic losses.

Efficacy and Baseline Sensitivity of Succinate-Dehydrogenase-Inhibitor Fungicides for Management of Colletotrichum Crown Rot of Strawberry.

The current management of Colletotrichum crown rot (CCR) of strawberry, caused by Colletotrichum gloeosporioides sensu lato, relies on the use of a few fungicide classes, particularly QoI fungicides. Since resistance to QoI fungicides has recently been detected, alternative fungicide groups are needed to control this disease. Our objective was to evaluate the efficacy of succinate-dehydrogenase-inhibitor (SDHI) fungicides in managing CCR. Five SDHI fungicides, fluopyram, isofetamid, penthiopyrad, fluxapyroxad, and benzovindiflupyr, were applied 2 days before or 1 day after inoculation of cultivar Strawberry Festival. SDHI treatments were compared with the most common fungicides used for CCR management, i.e., thiophanate-methyl, pyraclostrobin, and captan. Benzovindiflupyr applied 1 day after inoculation was effective in reducing plant mortality and disease development. The baseline sensitivity of C. gloeosporioides isolates was determined in vitro using a spiral gradient dilution assay. The EC50 for benzovindiflupyr and penthiopyrad varied from 0.08 to 1.11 and 0.45 to 3.17 µg/ml, respectively, whereas the other SDHI fungicides did not inhibit fungal growth. If registered, benzovindiflupyr could serve as an alternative to manage CCR in Florida.

Sources of Inoculum and Survival of Macrophomina phaseolina in Florida Strawberry Fields.

Macrophomina phaseolina, the causal agent of charcoal rot, affects strawberry crowns, inducing plant collapse. The fungus survives in the soil through the production of microsclerotia and is usually controlled by preplant fumigation of soil. However, in the 2016 to 2017 Florida strawberry season, even after soil fumigation, about 30% plant mortality still occurred in plastic-covered beds that were used for a second season and where crop residue (mainly old strawberry crowns) was disposed of between beds. Therefore, this study was conducted to determine if M. phaseolina can survive on strawberry debris over summer in Florida and if so, verify whether strawberry debris might act as a source of inoculum for new transplants. Crowns from the previous season were collected from commercial farms where charcoal rot had been reported, and M. phaseolina was recovered from all samples. In a research field, infected crowns were buried in the soil at different depths and retrieved every 2 weeks during the summer. After 8 weeks, M. phaseolina could be recovered at all depths. Moreover, inoculation of strawberry plants by drenching the soil, dipping roots, or spraying leaves with a M. phaseolina microsclerotial suspension from pure cultures or infected crowns produced symptoms with differences in incubation periods depending on cultivar susceptibility. Furthermore, infected crowns disposed of in the aisles between beds or buried next to new transplants of cultivars Strawberry Festival, Florida Beauty, and Winterstar induced charcoal rot, with the level of aggressiveness depending on the cultivar susceptibility and inoculum placement in the field.

The Importance of Selecting Appropriate Rotation and Tank-Mix Partners for Novel SDHIs to Enhance Botrytis Fruit Rot Control in Strawberry.

Botrytis fruit rot (BFR), caused by the necrotrophic fungus Botrytis cinerea, is the most important disease of strawberry and is mainly controlled by applications of fungicides from multiple chemical groups. To develop more effective and sustainable BFR management programs, field trials were conducted to evaluate the efficacy of fluopyram and penthiopyrad, two newly registered succinate dehydrogenase inhibitors (SDHIs), rotated or tank mixed with the multisites thiram and captan or the single-sites fludioxonil and fenhexamid. The treatments were applied at two different strawberry fields during the 2013-14 and 2014-15 seasons. Overall, tank mixtures of fluopyram and penthiopyrad increased yield and reduced BFR better than rotations with the same fungicides. The multisite thiram tank mixed with fluopyram reduced BFR incidence by 63 to 86% versus 56 to 84% when the two fungicides were rotated. Thiram tank mixed with penthiopyrad reduced BFR incidence by 55 to 72% versus 42 to 66% when rotated. Captan rotated or tank mixed with fluopyram had a positive effect on yield and BFR incidence, whereas the combination of captan with penthiopyrad had negative impacts. Similarly, the single-site fenhexamid had significant positive impacts when rotated or tank mixed with fluopyram but resulted in poor BFR control when combined with penthiopyrad. The rotation of fludioxonil with both SDHIs had a significant positive effect, although its combination with fluopyram was more effective. The multirotation consisting of both SDHIs and different multi- and single-site fungicides did not provide a greater efficacy than the dual rotation or tank-mixture programs. Our findings suggest more scrutiny is needed when recommending tank-mixture or rotation partners for new fungicides to ensure compatibility and enhanced BFR management. Future recommendations should emphasize the importance of such selections at an early stage for delaying fungicide resistance development and extending the lifespan of at-risk fungicides.

A Quantitative Synthesis of the Efficacy and Profitability of Conventional and Biological Fungicides for Botrytis Fruit Rot Management on Strawberry in Florida.

Botrytis fruit rot (BFR) is a major disease that affects strawberry production in Florida and worldwide. BFR management relies on frequent fungicide applications. A meta-analysis was conducted on the outcomes from nine field trials to evaluate the efficacy and profitability of conventional and biological fungicides compared with a nontreated control (NTC). All trials were conducted in Florida between the 2005/06 and 2016/17 growing seasons. Fungicide treatments were applied weekly, and plots were harvested twice a week for yield and BFR incidence quantification. Treatments were grouped into four categories: NTC, multisite only (Thiram), Standard (captan alternated with fludioxonil + cyprodinil), and Bacillus. Following primary analyses, a random effects network meta-analytical model was fitted to estimate the mean yield and BFR incidence responses for each treatment group and to compare means between pairs of groups. The Thiram and the Standard treatment groups increased yield by 378.8 and 502.2 kg/ha/week, respectively, compared with the NTC. The yield difference between Bacillus and NTC was not statistically significant. Besides increasing yield, Thiram and Standard also reduced BFR incidence by approximately 10% compared with the NTC. The mean yield responses and among-study variability from the meta-analysis were used to estimate the probability of a given yield response in a new future trial. The Standard and Thiram treatment groups showed higher estimated probabilities of increasing yield and resulting in a profitable return on application investments than the Bacillus group of treatments. The results from this study provide growers with information that will aid their decision-making process regarding BFR management.

Effect of Formulations of Allyl Isothiocyanate on Survival of Macrophomina phaseolina from Strawberry.

Management of Macrophomina phaseolina, causal agent of charcoal rot in many crops worldwide, including strawberry, has become more challenging since the phase out of methyl bromide (MeBr). The search for a fumigant equally effective as MeBr to control soilborne pathogens has been extensive. Allyl isothiocyanate (AITC), a biofumigant recently registered in the United States, was evaluated at different rates, formulations, fumigant combinations, and application methods in the fall of 2014 and 2015 at two research facilities in Balm and Dover, FL. The efficacy of treatments was determined by evaluating the survival of M. phaseolina inoculum on infested corn-cob litter buried in bags 7.6 and 20.3 cm deep in the center, and 7.6 cm deep in the side, of plastic mulched raised beds. The biofumigant was shown to be more or as effective in reducing populations of M. phaseolina in the soil compared with standard fumigants, such as chloropicrin and 1,3-dichloropropene with chloropicrin. Thus, AITC is a promising biofumigant alternative for managing charcoal rot of strawberry, particularly in organic production systems, and should be evaluated for the management of other soilborne pathogens.

Meta-Analysis of a Web-Based Disease Forecast System for Control of Anthracnose and Botrytis Fruit Rots of Strawberry in Southeastern United States.

Strawberry production in Florida and South Carolina is affected by two major diseases, anthracnose fruit rot (AFR) and Botrytis fruit rot (BFR), caused by Colletotrichum acutatum and Botrytis cinerea, respectively. The effective management of both diseases traditionally relied on weekly fungicide applications. However, to improve timing and reduce the number of fungicide sprays, many growers follow the Strawberry Advisory System (StAS), a decision support system for forecasting fungicide applications based on environmental conditions and previously developed models. The objective of this study was to perform a meta-analysis to determine the effectiveness of the StAS for AFR and BFR management compared with a calendar-based spray program. Thirty-nine trials were conducted from 2009 to 2014 in Florida and South Carolina commercial strawberry fields. Meta-analysis was conducted to quantify the treatment effects on four effect sizes, all based on the difference in response variables for StAS and the calendar-based treatments in each trial. The mean difference in BFR incidence, AFR incidence, yield, and number of marketable fruit between the two treatments was not significantly different from 0 (P < 0.05). However, the number of fungicide applications per season was reduced by a median of seven when using the StAS, a 50% reduction in sprays compared with the calendar-based approach. Effect sizes were not influenced by location or the favorability of the environment for disease development. These findings indicate that use of StAS in commercial fields is effective in controlling fruit rot diseases with no reduction in yield while substantially reducing fungicide applications.

Multi-domain automated patterning of DNA-functionalized hydrogels.

DNA-functionalized hydrogels are capable of sensing oligonucleotides, proteins, and small molecules, and specific DNA sequences sensed in the hydrogels' environment can induce changes in these hydrogels' shape and fluorescence. Fabricating DNA-functionalized hydrogel architectures with multiple domains could make it possible to sense multiple molecules and undergo more complicated macroscopic changes, such as changing fluorescence or changing the shapes of regions of the hydrogel architecture. However, automatically fabricating multi-domain DNA-functionalized hydrogel architectures, capable of enabling the construction of hydrogel architectures with tens to hundreds of different domains, presents a significant challenge. We describe a platform for fabricating multi-domain DNA-functionalized hydrogels automatically at the micron scale, where reaction and diffusion processes can be coupled to program material behavior. Using this platform, the hydrogels' material properties, such as shape and fluorescence, can be programmed, and the fabricated hydrogels can sense their environment. DNA-functionalized hydrogel architectures with domain sizes as small as 10 microns and with up to 4 different types of domains can be automatically fabricated using ink volumes as low as 50 µL. We also demonstrate that hydrogels fabricated using this platform exhibit responses similar to those of DNA-functionalized hydrogels fabricated using other methods by demonstrating that DNA sequences can hybridize within them and that they can undergo DNA sequence-induced shape change.

A reassessment of the fungicidal efficacy of 1,3-dichloropropene, chloropicrin, and metam potassium against Macrophomina phaseolina in strawberry.

BACKGROUND: The effectiveness of metam potassium, 1,3-dichloropropene, chloropicrin, and different ratios of 1,3-dichloropropene and chloropicrin on the reduction of natural and artificial inoculum of Macrophomina phaseolina were investigated in laboratory and field experiments. Additionally, a multivariate meta-analysis with data from six field trials conducted in Florida from 2012 to 2018 was performed. RESULTS: In small-plot field experiments using drip stakes, the highest rate (468 L ha-1 ) of metam potassium was most effective in controlling M. phaseolina in infected crowns buried at 15.2 cm from the point of fumigant injection, whereas none of the rates was able to reduce inoculum buried at 30.5 cm. In closed-container experiments, use of the highest rate of 1,3-dichloropropene (168 kg ha-1 ) resulted in the highest level of pathogen control. Different rates of chloropicrin also reduced inoculum when compared to the non-treated control. 1,3-dichloropropene + chloropicrin at different ratios were also highly effective in controlling M. phaseolina. Results from the meta-analysis of open-field experiments indicated that metam potassium and 1,3-dichloropropene + chloropicrin (63:35, v:v) treatments were significantly more effective in reducing M. phaseolina than the 1,3-dichloropropene + chloropicrin (39:60, v:v) treatment; however, metam potassium was not as effective at the side of the beds. CONCLUSION: 1,3-dichloropropene alone and in mixture with chloropicrin were more effective in reducing inoculum of M. phaseolina than chloropicrin alone, indicating the fungicidal efficacy of 1,3-dichloropropene. Formulation with higher 1,3-dichloropropene concentration performed better than the formulation with higher chloropicrin concentration in field trials. Metam potassium was effective when applied at the highest rate, but with limited lateral movement perpendicular to the drip irrigation line. © 2022 Society of Chemical Industry.