From left: ‘Caliente 199’ mustard cover crop; chopped, incorporated, cover crop for packed into
surface soils for biofumigation; healthy butternut squash atop rolled rye mulch in reduced tillage
treatment, Hudson Valley, 2015 & 2016.
Phytophthora blight (PB) is a potentially devastating crop disease and top concern for vegetable growers in the Northeast (including the northeastern Midwest) where susceptible cucurbit and nightshade species of crops contribute to major portions of farm incomes and to the greater vegetable industry. Soil health improvement has been proposed as a fundamental component of an integrated PB and general soil-borne disease management program. Certain brassica cover crops are capable of providing biofumigation services to soils with high soil-borne pathogen loads, and reduced tillage (RT) can allow for soils to regenerate functions that further mitigate soil-borne diseases. This project is aimed at increasing grower awareness and adoption of integrated PB and general soil-borne disease management through demonstration and research trials that combine the novel components 1) of biofumigation with brassica cover crops and 2) reduced tillage (RT) on six NY farms and at Cornell’s Long Island Horticultural Research and Extension Center (LIHREC).
By the end of 2015, seven collaborating growers had completed a total of 13 on-farm trials with brassica cover crops for biofumigation. Throughout winter 2016, biofumigation information and preliminary 2015 trial results were disseminated to a minimum of ~285 growers via educational events. In 2016, four remaining grower collaborators (from trial year 2015) followed their biofumigation trial year with RT treatments; one grower in Long Island opted out of the RT trial year, and two former grower collaborators from western New York failed to successfully implement the RT component at their sites.
All four remaining grower-collaborators successfully completed a RT vs. “grower standard” control comparison with a cucurbit response crop across nine total replications. The research team collected data on cover crop biomass, yield, PB incidence, soil infiltration rates, and a soil health assay in 2016. Similar to 2015, weather was not conducive to a proliferation of PB at the trial sites. Phytophthora incidence was therefore low, and, at most sites, non-existent; our ability to collect evidence of treatment effects related to Phytophthora was therefore reduced again in 2016. Results will be analyzed and educational materials developed throughout 2017-18. In addition to growers that tried brassica cover crops for biofumigation in 2015 (see 2015 report), 2-3 more growers in the Hudson Valley region were noted to have informally tried ‘Caliente’ mustard for biofumigation for the first time in 2016 as a result of this project.
The soil-borne pathogen Phytophthora capsici, which causes Phytophthora blight (PB), increasingly threatens economically important vegetable crops in the northeastern US annually constituting 33-40% of all vegetable crops grown (~300,000 acres). Phytophthora capsici persists in soils for many years without a crop host present. Infested fields on average lose ~30% of susceptible crops and ~80-100% in wet years, even with fungicides. Contained incidents become widespread after flooding events, and more frequent instances of heavy rainfall are a proven emerging component of the northeastern climate. Phytophthora capsici is established in 25 NY counties, and epidemics have been likewise reported by Extension in five other northeastern states. Four grower-informed groups in the northeast list PB management as a top research priority. Soil biofumigation with brassica cover crops and reduced tillage are promising components of integrated soil-borne disease management programs that will remain underutilized without better quantification of effects and participatory research with growers.
Forty vegetable growers across three regions of NY will integrate multiple soil-borne disease management practices that may include biofumigation with brassica cover crops and reduced tillage on at least an 5 acres per farm, recovering $1000 - $4000 per acre otherwise spent and/or lost on diseases like Phytophthora blight.
We hypothesized that 1) biofumigation will reduce soil-borne pathogen inoculum in soils, and that 2) reduced tillage and cover crops will further reduce opportunities for pathogen inoculum spread and viability, leading to reduced crop disease and increased yields. Using PB as a proximal indicator of effects of these practices on soil-borne diseases, we also expect additional increases in soil infiltration rates, nitrogen and carbon returned to soils in cover crops, and general soil health.
Our on-farm research was conducted in three regions of NY representing a spectrum of agroecosystems and soils found in northeastern vegetable production regions, and at Cornell’s Long Island Horticultural Research and Education Center (LIHREC). The LIHREC has a long history of PB research. Our field research objectives were to 1) establish a two-year, field-scale, on-farm trial (two farms/region) and 2) a corresponding plot-scale trial at Cornell’s LIHREC to assess effects of biofumigation with brassica cover crops, reduced tillage, and these factors integrated as a soil health program that guards against soil-borne disease proliferation. To assess potential treatment effects of interest, we measured cash crop yields, PB incidence, soil infiltration rates, cover crop carbon and nitrogen content, and conducted a Cornell soil health assessment.
Year 1 on-farm treatments included PB susceptible crops planted after grower standard control treatments and after brassica cover crops incorporated for biofumigation. Year 2 on-farm treatments included cucurbits planted into grower standard controls and reduced tillage treatments that were biofumigated in year 1. Growers chose which PB susceptible crop to plant (cucurbits suggested), brassica cover crop species/variety, their control (grower standard) treatment, and elected any additional treatments of interest or replications. Our plot-scale trials included similar treatments to the on-farm trials, with additional comparisons of 1) spring vs. winter brassica cover crop species, 2) fall vs. spring biofumigation timings, and 3) a full 2-year reduced tillage treatment that included brassica cover crops and a living mulch (white clover). Our original experimental design also included split-plot treatments with applications of beneficial organisms (biocontrols/biofungicides), but this component was abandoned due to logistical constraints.
Our on-farm experimental design uses farm as the replicate/block where each farm will implement a minimum of one replication of each treatment; two collaborating growers elected to add more replications and/or treatments within their sites. Grower standards controls varied, but were controlled enough to maintain a biofumigation vs non-biofumigated treatment contrast; one grower used an oat/pea cover crop control in year 1, another used reduced tillage in both years 1 and 2 on the control side, and several used reduced tillage in both treatments in year 2 only. At LIHREC we implemented a randomized complete block design with four replications of each treatment. Winter brassica (‘Nemat’ arugula) cover crops began in mid-September 2014, spring brassica cover crops (‘Caliente 199’ mustard) were planted between mid-April and early-May 2015, and fall sown brassicas (‘Caliente 199’ mustard) were planted in early-August 2015. Successful brassica cover crops were terminated 2-4 weeks after flowering stage (after ~50-60d of growth) with fail or rotary mowing, incorporation, and culti-packing for biofumigation.
Cucurbit cash crops were planted at sites in early summer 2015 within 1-2 weeks after biofumigation. All rye cover crops used in standard grower practices in year 1 or before reduced tillage were planted between late-September to early-October. Rye crops were either terminated in early mid-April in tillage-based treatments, or grown to anthesis stage and rolled flat to form a dead mulch in Mid-may before zone-tilling for cucurbit plantings in early summer in 2015 and/or 2016.
Our on-farm data analysis will focus on biofumigated + reduced-till vs. control treatments using a mixed model analysis (treatments as fixed effects, and farm/block/replicate as random effects). Treatment effect assessments from the LIHREC trials will likewise use mixed model analyses (treatments and as fixed effects, and block/replicate as random effects).
We are conducting ongoing records of grower experiences in implementing these novel practices to gain insight into new perspectives on management and potential barriers to adoption, including a prepared evaluation sheets/questionnaires before the end of 2018. In anticipation of already identified barriers related to investments into new cultural practices (learning curve, equipment, etc.), we are also collecting data on indicators of conservation benefits including 1) organic carbon returned to soils and nitrogen recycled to soils in cover crops, and 2) soil infiltration rate changes, to importantly document a wider spectrum of benefits/incentives incurring from adopting these multifunctional practices.
Fall planted ‘Nemat’ arugula cover crop biomass data was collected from two on-farm sites in late fall 2014 as a precautionary measure in case of winterkill. Data from another two sites in western NY could not be collected because of an early snowstorm that covered the trial site in several feet of snow. All arugula planted in 2014 (including the western NY sites) experienced 100% winterkill by spring 2015, so biomass accumulation was low. On average, the winterkilled ‘Nemat’ arugula cover crops produced 761-2174 lbs/ac of biomass (containing 288 to 671 lbs/ac of C and 22-80 lbs/ac of N) that were returned to soils.
Results from the 2015 dataset are preliminary/exploratory in the context of this project- the core measure of treatment response being examined is the potential cumulative effects of biofumigation + reduced tillage (RT) treatment to be measured in the second project year.
In 2015, the research team collected data on spring brassica cover crop biomass, pumpkin yield, and Phytophthora blight incidence. On-farm data was collected at three sites (two in Long Island and one in the Hudson Valley) with a total of four replications (one site had two replications). Each on farm site had standard grower practice vs. biofumigation treatment comparisons. The same datasets were also collected at the LIHREC trials in 2015, though the LIHREC used a kubocha winter squash response crop instead of pumpkin.
Spring mustard biofumigation cover crops at the farm sites returned between 735-2017 lbs/ac C and 45-164 lbs/ac N of biomass in biomass to soils (1305-5391 lbs/acre total). Of those, biofumigation cover crops that were managed accordingly with recommended planting timings and fertility returned 1483-2017 lbs/ac of C and 125-164 lbs/ac N to soils in biomass (3993-5391 lbs/ac total). Conditions were generally droughty throughout spring/early summer 2015, but biofumigant cover crop biomass was anomalously lower than usual in the spring-planted mustard plantings in Long Island (despite prudent management), where drought was severe. Conversely, A fall-planted mustard planting at the LIHREC escaped the earlier severe drought conditions, and produced nearly 3x more biomass (1769 lbs/ac C and 174 lbs/ac N returned in biomass; 4347 lbs/ac total) than the droughty spring plantings.
There was insufficient evidence of statistical differences between biofumigation and standard grower practices on pumpkin yield and PB incidence in the on-farm trials (p = 0.64), despite a 1.5 ton/ac greater numeric yield average (arithmetic mean) for pumpkins following biofumigation in 2015. Phytophthora incidence was negligible across all treatments at all trial sites, likely due to dry conditions that persisted throughout the summer. At the plot-scale trials at the LIHREC, the only difference in individual treatments was in winter squash yields following the arugula/white clover full-RT treatment, where squash yielded 5.4 tons/ac lower than the other treatments. When treatments sharing similar attributes were contrasted as groups though, there were distinct differences in yield between spring-planted mustard biofumigation treatments and the treatments that contained the failed fall-planted arugula (not able to be used for biofumigation treatment due to winterkill) and the winter rye control. This occurred despite the low mustard biomass produced from the preceding spring-planted mustards. Squash in these spring-biofumigated treatments yielded 3 tons/ac greater when contrasted with the failed arugula and rye-containing treatment group (p < 0.01); even when these treatments are contrasted with the rye control alone, there was marginal evidence of a 1.5 ton/ac greater yield (p = 0.10) following spring biofumigation.
Because of the lack of evidence that Phytophthora blight affected yields though, we hypothesize that the trends observed in yield thus far may be from 1) differences in fertility as affected by the mustard cover crops, and/or, possibly by 2) general reductions in low-level soil-borne pathogen loads following biofumigation in the spring mustard treatments. The opportunity to detect evidence of potential treatment differences may also have been hindered by loss of some trial sites (lowered statistical power) and by general lack of Phytophthora incidence in the field this in 2015.
On Farm Trials: Four collaborating growers successfully completed a biofumigation + RT vs. “grower standard” control comparison with a cucurbit response crop with nine total replications. The research team collected data on rye cover crop biomass, cash crop yield, PB incidence, soil infiltration rates, and a conducted a soil health assay in 2016.
Like 2015, preliminary analyses of on-farm yield response to treatments again are showing insufficient evidence of differences between treatments (p = 0.29). This is despite a 1.4 ton/ac greater numeric average cucurbit yield (arithmetic mean) and 0.29 ton/ac less average numeric yield lost PB to for cucurbits following biofumigation in 2016.
Yields of squash at the LIHREC did not result in the same pattern as 2015. Highest yielding treatments included brassica cover crops, though not necessarily biofumigation. Contrast comparisons between biofumigation and non-biofumigated treatments lacked evidence of a difference (p = 0.60), and interestingly, further contrast analyses revealed that tillage-based treatments yielded 1.6 tons greater than RT treatments (p = 0.04). One biofumigation + RT treatment (2015 spring-planted mustard biofumigation > 2016 RT Rye) did not yield significantly different than the base control treatment (2015 rye > 2016 tilled Rye). Although the top yielding treatment included biofumigation (2015 spring-planted mustard biofumigation > 2016 tilled Rye), only one biofumigation + RT treatment (2015 fall-planted mustard > 2016 RT Rye) yielded intermediately between this top yielding treatment and the base control treatment.
These unanticipated yield results, contrary to the hypothesis may have been the result of number of factors. Fertility may have been a factor, as RT treatment and cover crops can be complicating in developing appropriate fertility programs. Also, again, like 2015, weather was not conducive to a proliferation of PB at the trial sites. Phytophthora incidence was therefore low, and, at most sites, non-existent; our ability to collect evidence of treatment effects related to PB was therefore reduced again in 2016. Grower choices of their standard practice were also not conducive for contrasting potential additive effects of RT to biofumigation treatments. Three of four collaborating growers chose to use RT in their control treatments, leaving biofumigation + RT vs. non-biofumigated + RT as the only comparison that could be made. One of these growers additionally used a field pea/oat cover crop as a comparison to the biofumigation cover crop; the pea/oat treatment is presumably yield-boosting due to the fixed-nitrogen contribution of the peas to the following crop. While a pea/oat cover crop does not offer biofumigation potential, yield responses of following crops may be less likely to contrast with those following brassica cover crops which also have yield boosting potential due to their nitrogen-rich residues (as a catch crop of residual soil N) alone. While these “grower standard” choices can be viewed as affirmative with regards to grower interest and adoption of soil health building practices, it likely diminished the opportunity for us to detect evidence of treatment differences compared to a more typical grower standard treatments that may only use limited rye cover crops, and conventional tillage.
Analysis of soil infiltration rates and soil health data are still being analyzed. Rye biomass data is also still under analysis to determine if there are any correlations to yield parameters.
Our educational program will utilize three central approaches to disseminate project-related information: 1) direct grower engagement through participatory research, 2) in-person educational and networking grower events, and 3) access to static educational resources (print, online, and audio-visual educational materials).
Our educational curriculum includes:
1. Understanding the Phytophthora capsici pathogen, its spread, and the causes and development of PB in agriculture.
2. Understanding biofumigation mechanisms, selecting appropriate biofumigation species/varieties, fertilization, cover crop termination timing, and biofumigation steps.
3. Reduced tillage approaches for PB/soil-borne disease management (ex: planting into zone-tilled rolled, mowed, or sprayed-out cover crops, or living mulches).
4. Integrating components of PB/soil-borne disease management, including biofumigation, reduced tillage, fungicides, biocontrol organisms, sanitation, in-field water management, and cultivar resistance.
5. Understanding additional benefits of soil health improvement from cover crops and reduced tillage (ex: improved nutrient cycling efficiency, soil organic matter maintenance, soil drainage/infiltration etc.).
6. Addressing potential observed barriers to adoption of novel PB management practices.
Potential regional grower peer mentors will be recruited through county Extension and involved through our participatory on-farm research component. Extension will guide grower collaborators through the on-farm research process, the steps of successfully biofumigating with a brassica cover crop, and using reduced tillage for combating soil-borne disease. Grower collaborators will serve as peer mentors facilitating adoption diffusion in each region, and Extension will help guide other growers adopting these practices as a result of the project. Other beneficiaries interested in adopting practices being employed in this project will be provided with on-demand individualized guidance and educational materials from Extension, and directed to an area peer mentor for support and perspective on successful adoption approaches. Through Extension, grower, and researcher networks, additional growers will be recruited to participate in annual field days in three regions of NY, to attend winter conferences, meetings and workshops, and explore static on-demand web resources.
Novel PB management practices will be demonstrated at field days, and results presented at statewide/regional winter workshops and conferences, a webinar, and in Extension publications and websites. A narrative record of producer experiences, and an integrated PB management and biofumigation “how-to” reference sheet and video will also be produced and made available on Cornell Extension websites. Key collaborator McGrath will additionally be able to disseminate our findings to growers, Extension, and researchers outside of NY at regional and national educational venues.
1) Six growers battling Phytophthora blight (PB) in three distinct regions of NY are recruited by Extension and guided through the process of choosing treatments and establishing a trial including a brassica cover crop for biofumigation and reduced tillage. Beneficiaries gain first hand experience with novel, integrated management tools for PB management. Beneficiaries learn the logistics of selecting and growing brassica cover crops for biofumigation, the biofumigation process, methods of reduced tillage that mitigate PB and soil borne disease, and enhanced understandings of soil health management.
This milestone was completed for the two 2014-15, and 2015-16 trial years. Seven (of a targeted six) growers trialed brassica cover crops for biofumigation vs. their standard practice, but three grower collaborators from 2014-15 chose not to continue the trials into 2016. Four (of a targeted six) collaborating growers continued participate for the reduced tillage (RT) portion of the trials in the Long Island and Hudson Valley regions. To offset the loss of data from lost grower collaborator trial sites, the remaining collaborators were encouraged to implement more than one replication at their site in 2016; at two Hudson Valley sites, one grower established two replications (of which, one was compromised), another grower established three replications, while another was able to establish four.
2) 75 growers attend field days (25/region) and learn about PB and integrated approaches to managing PB and soil-borne diseases through viewing trials and from the project’s grower collaborators and research team.
The project team added at least 60 grower contacts to this portion milestone through three regional grower twilight meetings in summer 2015; ~52 growers were previously introduced to the project in summer meetings before the 2015 project year.
3) 300 growers total attending winter conference/meeting presentations will learn about integrated approaches to managing PB and soil-borne diseases and year 1 trial results.
Presentations during winter of 2016 disseminated information on biofumigation practices and preliminary trial results, reaching at least ~285 growers (and other stakeholders). The presentations were given in a statewide grower conference in Central NY, at a regional grower meeting and a statewide conference in NY’s Capital District region, and at another grower meeting in NY’s Hudson Valley region in 2016. A link to the one of the project-related presentations given in 2016 is provided below, at end of this section. Approximately 33 stakeholders were connected to the project via winter meetings before the 2016 project year.
4) 75 growers attend field days (25/region) and learn about PB and integrated approaches to managing PB and soil-borne diseases through viewing trials and from the project’s grower collaborators and research team.
Due to 1) project demonstration and dissemination events in summer 2015, 2) a considerable project information dissemination effort at 2016 winter meetings, and 3) a lack of new information from the project to share, the research team opted to refrain from holding dedicated project-related summer demonstration events in 2016. We also alternatively decided to bring in out-of-state guest speakers to talk about the components related to the project (see Milestone 5), and to hold project demonstration events only after we have new project information to share before. The project efforts were nonetheless shared in 2016 once in summer at a general IPM grower event in the Hudson Valley, and at two other general IPM grower events in western NY, reaching an additional ~70 growers and stakeholders total. The western NY region would have benefited from a demonstrative event in 2016, but their demonstration sites were lost. To help compensate for these lost trial/demonstration sites, we alternatively have decided to make an extra effort to disseminate project-related information and final project results throughout the final project year in western NY. The 2017 season was disrupted by the project PI relocating to Washington State. This milestomne is marked as in progress still because demonstration events and project results dissemination at summer grower field events are anticipated for 2018.
5) 300 growers total attending winter conference/meeting presentations will learn about integrated approaches to managing PB and soil-borne diseases and project results. January-March 2017.
Three different events with presentations on subjects related to the project were completed in winter 2017: 1) Farmer and biofumigation expert Dale Gies of High Performance Seed in eastern Washington was a featured speaker at an annual statewide grower event in Central NY, 2) a presentation was given by the reserch team at a regional grower event in Long Island, and 3) a grower event in Western NY featured Extension faculty expert Dr. Mary Hausbeck from Michigan State University in a focused session about integrated Phytophthora blight management. These presentations connected another ~170 stakeholders to the project. This milestone is still in progress because more connections are anticipated from scheduled talks on the project throughout winter 2018 in Indiana, New Jersey, and Vermont.
6) 1500 beneficiaries total nationally will learn about our biofumigation with brassica cover crops and integrated approaches to managing PB and soil-borne diseases via the above contacts, and Extension materials posted online, a webinar, and an instructional video.
One research team collaborator has spoken to researchers in the greater Great Lakes region (including Canada) about the project components. The team is also building an online page of project-related information as an on-demand resource that is expected to substantially increase exposure to the project and its components: http://ulster.cce.cornell.edu/integrated-phytophthora-management-biofumigation-reduced-tillage. We have also been taking video footage intended for development of an educational video and illustrative animations, some of which is already included on resources at the above webpage.
Greater regional and national impact is expected to continue to grow throughout 2018 following scheduled talks in Indiana, New Jersey, and Vermont, and a public webinar. The project lead (former PI O’Dea, now at Washington State University) anticipates continuing work with biofumigation in the Pacific Northwest region as a result of this project.
7) 40 growers in three distinct regions of NY (10-15/region) are mentored by our grower collaborators and/or Extension in implementing integrated approaches to PB and/or soil-borne disease management in each respective region represented in the project.
In addition to our six formal core collaborators, four other Hudson Valley region growers trialed brassica cover crops for biofumigation in fall 2014 and/or in late summer 2015 under the guidance of Extension, and at least 2 to 3 other Hudson Valley growers trialled cover crops for biofumigation in spring and fall 2016. To date, at least three of these growers have voiced the intent to use biofumigation again, and one grower intends to adopt RT practices as a result of the project. Other growers in Long Island are also continuing to adopt brassica cover crops, biofumigation, and RT as a part of managing various soil-borne diseases.
Milestone Activities and Participation Summary
Performance Target Outcomes
Integrating multiple soil-borne disease management practices that may include biofumigation with brassica cover crops and reduced tillage.
To date, at least 13 growers have tried brassica/biofumigation and/or reduced tillage for soil borne disease management as a result of the project. We anticipate an increases impact towards our performance target in 2018 after disseminating the final results of the project and conducting a formal survey of growers in each region on adoption of integrated Phytophthora blight and general soil-borne disease management, biofumigation with brassica cover crops, and RT.
Additional Project Outcomes
Growers that have been involved in this project thus far under the guidance of Extension (either formally or informally) have generally expressed and/or exhibited notable gains in understanding how to manage brassica cover crops, the biofumigation process, reduced tillage, and Phytophthora blight and soil health management in general. For the research team also, the process of working with growers on-farm has highlighted what the barriers to successful adoption of brassica cover crops and biofumigation may be for growers across the state and greater Northeast region, and what components may improve research and educational efforts.
Multiple factors have been elucidated through the project regarding adoption and viability of integrated soil borne disease management, biofumigation and reduced tillage, including:
- Growers that had grown brassica cover crops before perceived general positive effects on subsequent cash crop yields and were further interested in quantifying the impact of their use in mitigating PB. Favor for the reduced tillage aspect was present for some growers, but less ubiquitous.
- In Western NY, the core of the interest was in using brassica cover crops, but growers in this region expressed crop rotation concerns (disease risk concerns) because brassica cash crops are common in this region. Western NY growers were also more unsure of the reduced tillage aspect; reduced tillage in this region is less widely adopted than in Long Island and the Hudson Valley, and growers were unfamiliar with the practice and lacked equipment. The western NY region has been the most difficult region to recruit collaborating growers and adoption for these reasons.
- Each arugula crop suffered complete winterkill even with timely fall seeding (early-mid September); four other Hudson Valley growers informally trialing ‘Nemat’ arugula in 2014 also experienced complete winterkill.
- In 2015 Growers experienced variable degrees of success completing the biofumigation process with fall-sown winter arugula and spring-sown mustard. Barriers to biofumigation success identified thus far were: 1) arugula will not overwinter in NY, 2) late plantings of spring mustard can reduce biomass and delay following cash crop plantings, 3) reluctance to provide sufficient fertility, pre-emptive weed control, and seedbed preparation 4) misunderstanding and reluctance to follow the steps of the biofumigation process, 5) concern about spreading disease and pests from brassica cover crops to brassica cash crops, and 6) apprehension about letting brassica cover crops grow after flowering for fear of them going to seed.
- An early observation of the arugula was variability in plant vigor due to an apparent strong response to available nutrient levels that varied across different soils. This attribute was held true for all brassica cover crops- they are extremely responsive to available N and will cycle it back to soils accordingly. Brassica cover crops growing with lacking fertility will not succeed as effective cover crops or biofumigants.
- Due to the lost potential of overwintering arugula and the difficulties of fitting timely spring mustard plantings into rotations, the research team decided to open a third late summer planting option to growers. This option allows growers to fill a niche in their rotations after early vegetable crops, and appears to be one of the more promising options, based on grower feedback.
- Grower collaborators largely did not face difficulty implementing reduced tillage (RT) treatments, even if it was their first time doing so. Typical to the strategy of RT, though, equipment remains a palpable restriction to potential adoption. One collaborating grower borrowed equipment that was available for public demonstration through an unrelated soil health initiative. This grower-collaborator plans to purchase RT equipment for the upcoming season based on how well the RT strategy worked to suppress weeds compared to their typical approach to weed control.
If applicable, a well-managed rolled cereal cover (especially rye) can be a considerably effective weed suppression component in RT systems (see figure below). Reduced tillage generally suffers from a stigma that it’s risky for weed control because of the loss of cultivation strategies, and sole reliance on herbicides for weed control. One of the original collaborating growers from the Long Island region who opted out of the RT trial portion in 2016 actually did so out of fear of poor weed control in their u-pick pumpkin operation.
- Timing the rye-kill operation is often difficult for growers; it is generally advised to wait until after anthesis/flowering before trying to kill rye. Several growers needed extra unanticipated measures to kill their rye cover. Some had to roll more than once or mow rye that stood back up, or apply herbicide after roller crimping. There were also variations in the density of the stands of rye at various sites. As expected, sites with thicker stands of rye overtly had thicker, more tenacious mulch layers that helped suppress weeds and keep cucurbit fruits from contacting soils. It is also worth noting that although Phytophthora blight (PB) incidence was very low across all sites in 2016- when PB wasfound on cucurbit fruits, it overwhelmingly seemed to appear where rye mulches were thin or absent and soils had direct contact with the fruit.
- Our most novel (i.e. experimental) treatment at the LIHREC, ‘Nemat’ arugula with white clover undersown (with cash crops zone-tilled into the clover living mulch), largely failed in spring 2015, and was reformulated (to a late summer/fall mustard undersown with white clover) but the clover failed again- both times due to poor establishment on the LIHREC’s coarse, droughty soils. It will remain unknown if this treatment would have been viable with good clover establishment, but it highlighted that clover establishment was very sensitive to a lack of soil moisture. Higher seeding rates may also have helped with clover establishment resiliency.