Hand-held Flame Cultivation: Developing a sustainable weed control method in cranberry production

Hand-held Flame Cultivation: Developing a sustainable weed control method in cranberry production

Summary

Dewberry (Rubus sp.) is a serious weed in commercial cranberry production. It spreads quickly, reduces yield, crowds out cranberry vines, and is very difficult to control with current methods. Flame cultivation (FC) may offer a non-herbicide option for management of this weed. Our preliminary work with hand-held FC has shown that relatively short exposures (6-9 sec) with an open flame FC can decrease dewberry biomass; other work showed that cranberry recovers well from exposure to FC. The goal of the proposed research is to identify the best timing and application recommendations for the practical use of FC for dewberry control in cranberry cultivation. To study the link between burning, effective weed control, and carbohydrate depletion, the field work will be combined with laboratory work that will provide information on the seasonal carbohydrate reserves in the dewberry plant. These data will be used to develop recommendations for the best time of year to use FC for dewberry control. The outcome of this study has the potential to reduce environmental and health risks by reducing chemical inputs, and to increase crop productivity by providing weed control. Information generated by this study will be disseminated to the cranberry growers via bogside workshops, newsletters, Extension meetings, web media, fact sheets or other appropriate forums.

Objectives/Performance Targets

Objective 1: Conduct a 2-year replicated on-farm study in the summer of 2011 utilizing hand-held FC for control of dewberry to investigate the effects of frequency and seasonal timing of FC applications. Qualitative measurements of stem number and length will be taken periodically, and aboveground biomass samples will be collected in 2012 at the conclusion of the study to evaluate treatment effects.

Completed: The experiment was established on a cranberry farm in East Wareham, Massachusetts in June of 2011. Plots 0.25 m x 0.25 m were established on bog edges were dewberry plants were growing. Qualitative measurements of dewberry stem number and lengths of stems were made for each plot on June 23, 2011. Plots were randomized within each replicate, received one of seven different treatments with an open flame handheld cultivator (no treatment, a single treatment in June, July or August, or two treatments June/July, June/August, or July/August). All treatments were replicated 5 times. End-of-season measurements of dewberry stem number and lengths of stems were made September 26, 2011 and September 28, 2011.
Plants within each plot were re-measured in June 2012. All aboveground biomass was collected from each plot June 19, 2012.

Objective 2: Analyze carbohydrates in root samples from dewberry plants treated with FC in a 2010 experiment (root samples to be collected in 2011) and in the proposed 2011 experiment (Objective 1, root samples to be collected in 2012) to gather quantitative data on how FC treatments affects the amount of dewberry reserve carbohydrates.

Completed: Roots from plants treated in 2010 were collected on June 27, 2011. Approximately 6-cm sections of roots 1 cm (the minimum size needed for the protocol) in diameter or larger were dried and ground according to the proposed protocol. They were analyzed with HPLC April 2012.
Roots from the 2011 experiment (Objective 1) did not meet the diameter > 1cm we had established for suitability for HPLC analysis. In addition to the 2011 experiment conducted under this grant contract, an identical experiment was conducted on dewberry plants that had been cultivated in a garden. Roots from this experiment were collected, dried and ground. They will be analyzed with HPLC in January 2013 in place of the roots from the experiment in this grant contract, but will yield similar information on the impact of the FC treatments on dewberry reserve carbohydrates.
The results of HPLC analysis from 2010/2011 samples and 2011/2012 samples will be statistically analyzed to test for differences in dewberry reserve carbohydrates between the different FC treatments in January 2013.

Objective 3: Conduct a replicated study of two untreated dewberry populations to determine seasonal variations of stored carbohydrates in dewberry. Due to the destructive nature of root sampling, areas need to be identified were dewberry are growing without cranberries present, but in conditions similar to those found on a commercial farm. One site will be an area adjacent to a commercial cranberry farm, and the other at area at the UMass Cranberry Station. This information will be used to refine FC timing, so that treatments are administered at the time when seasonal reserves are known to be the lowest.

Completed: Root samples were collected from two sites at five collection dates in 2011 based on dewberry phenological stage: bud break, full leaf expansion, flowering, fruit ripe, and onset of dormancy. Four entire plants were excised from each site at each sampling time. Approximately 6-cm sections of roots 1 cm in diameter or larger were dried and ground according to the proposed protocol. Root samples were analyzed with HPLC in April 2012.
Although not within the scope of the original grant proposal, we had the time to repeat this study again in 2012. The samples will be analyzed with HPLC in January 2013, and the results of HPLC analysis from 2011 2012 samples will be analyzed for seasonal and phonological trends in dewberry reserve carbohydrates January 2013.

Accomplishments/Milestones

In April of 2012 HPLC was performed on the dewberry root samples collected in 2011. These samples were from the 2010 flame cultivator farm study and the study on seasonal fluctuations of carbohydrate reserves in the dewberry plants. We were also able to collect an additional year of data for the study (in 2012) on the seasonal fluctuations of carbohydrate reserves in the dewberry plants. Two additional populations of dewberry plants were identified in April 2012. Dewberry roots were sampled from these populations when dewberry plants were at bud break (April 4, 2011), full leaf expansion (May 11, 2011), and flowering (June 5, 2011). These root samples were dried and ground in preparation for HPLC analysis.
Qualitative measurements of dewberry stem number and lengths of stems were made for each plot of the flame cultivator study on June 19, 2012, approximately 1 year after the initiation of the experiment. All the aboveground plant material was collected from each plot, dried, and weighted. We had planned to collect root samples from each plot for HPLC analysis. However the roots from plants in this study did not meet the diameter ? 1 cm criteria.
In addition to farm study outlined in this SARE contract, we had also initiated an identical experiment on cultivated dewberry plants in an area adjacent to a bog. We collected root samples from this study on June 25, 2012, and plant to perform HPLC on these dewberry roots in place of the root from the farm study that we were unsuitable for HPLC.
Dewberry root samples were taken from the two populations being studied for the seasonal carbohydrate fluctuation study when dewberry plants had ripe fruit (August 1, 2012) and after they had become dormant (October 24, 2012). This stage was determined to be when all leaves were either absent or entirely red. These root samples were dried and ground in preparation for HPLC analysis.
In January 2013, HPLC analysis will be done for roots collected from the 2011 experiment, as well as all of the roots collected in 2012 for the seasonal fluctuations of carbohydrate reserves study.
Preliminary statistical data analysis has begun on the qualitative measurements of stems length, stem number, and aboveground biomass. After HPLC analysis has been completed, those data will be statistically analyzed.
Aside from the changes noted on using dewberry roots from a different but identical flame cultivator study for HPLC, this study is progressing according to schedule. We were even able to collect an additional year of data for the study on seasonal fluctuations in dewberry root reserves that we had not anticipated. All field work has been completed, and data analyses have started.
Results, conclusions, and potential management recommendations made from information generated by this study will be disseminated to the cranberry growers via bogside workshops, newsletters, Extension meetings, web media, fact sheets or other appropriate forums. Results will also be submitted for publications in refereed scientific journals, and presented at professional and extension meetings.

Impacts and Contributions/Outcomes

I anticipate presenting the results of this work at the UMass Cranberry Station Annual Research and Update Meeting in January 2013, which is attended by over 250 growers. The presentation will also be made available online through the UMass-Amherst ScholarWorks website (a digital repository). I also plan to present results from this project at the joint Weed Science Society of America/Northeastern Weed Science Society Annual Meeting in February, 2013.
This work will help to support agricultural sustainability by demonstrating that chemical alternatives for weed management can be successfully employed on cranberry bogs to control dewberry, and also helping to inform growers about the most effective time to target these weeds.. This information on timing will be applicable to other weed control techniques such as pulling or digging out the weeds, clipping plants, or even some types of herbicide applications. Flame cultivation has the potential to reduce environmental and health risks by reducing chemical inputs, and to increase crop productivity by providing more effective weed control.

Collaborators: