Final report for OS16-094
Peach growers in the Southeast must control many pests and diseases to be able to produce high quality fruit. As a result, conventionally produced, Southeastern peaches are probably among the most frequently sprayed peaches in the U.S. due to the favorable climate for pests and diseases and the absence of resistant cultivars. Many conventional growers are trying to reduce cost and resistance risk by reducing the number of pesticide applications to their crop to deliver quality products to their customers, but pest and disease control remains their main challenge. On the other hand, production of organic peaches is extremely difficult under the humid conditions of the Southeast, which is why very few growers have taken on this challenge. The only certified organic producer in South Carolina reports significant problems controlling plum curculio and brown rot despite weekly applications of organically approved pesticides. The low efficacy of available products sometimes require more than one application per in organic orchards especially before and after rainfall. In addition, consumer demand for high quality and residue-free fruit is growing, which poses a significant challenge for the sustainability of Southeastern fruit production. Thus, the need for practices to reduce insecticide/fungicide applications in conventional orchards, and to increase the production of high quality organic peaches in the Southeast is a critical issue that deserves attention and research.
A strategy that is being used in some other parts of the world to protect the fruit from pests and diseases, and to produce high quality fruit is the use of paper bags. This proposal seeks funding to investigate horticultural practices needed to apply bags to trees of an entire orchard. We will focus on two treatments [unbagged fruit (control) and bagged fruit], determine the effect of bagging on fruit quality and disease incidence, and perform an assessment of costs and benefits. This research will be carried out in two farms: one conventional farm (Titan Farms) and one organic farm (Watsonia Farms).
- To develop a strategy to increase yield of high quality peaches and reduce reliance on pesticides in conventional and organic peach orchards.
- To communicate results and disseminate this innovative strategy to growers in the Southeastern United States
Peach growers in the Southeast must control many pests and diseases to be able to produce high quality peaches. As a result, conventionally produced, Southeastern peaches are probably among the most sprayed peaches in the U.S. due to the favorable climate for pests and diseases and the absence of resistant cultivars. The frequent application of pesticides is of environmental concern, poses residue problems, and promotes resistance development. In addition, consumer demand for high quality and residue-free fruit is growing, which poses a significant challenge for the sustainability of Southeastern fruit production. The alternative to conventional production would be organic production of peaches. But production of organic peaches is extremely difficult under the humid conditions of the Southeast and consequently very few growers are taking this chance. Organic producers report an even higher number of spray for pest and disease control due to tighter application intervals required for less effective products. Thus, the need for practices to increase the production of high quality organic peaches and to reduce insecticide/fungicide applications in conventional orchards in the Southeast is a critical issue that deserves attention and research.
A strategy that is being used in other parts of the world to protect the fruit from pests and diseases, and to produce a high quality peach is the use of paper bags. Fruits are individually bagged by hand at early stages of fruit development, and paper bags protect the fruit during the rest of the season from diseases, insects, and sunburn. In our research, we bagged peaches on two acres at a conventional farm and at an organic farm. Bags were placed in Spring, after thinning (April). It took approximately 1 hour per person to bag all the fruit on a tree (mature tree ~ 400 fruit; 2 acres ~ 280 trees). One day before bagging, trees were sprayed with fungicide so that there was no disease inoculum and the fruit was sanitized before placing the bag. After fruit was bagged, trees did not receive any cover spray.
Upon harvest, all bags were riped open; ripen fruit was harvested and fruit that needed a few more days were left on the tree (with the bag, just open at the bottom) and harvested a few days later. We measured marketable yield and number of rotten fruit in trees with bags and without bags. We also measured fruit quality (size, mass, total soluble solids, and acidity) and evaluated postharvest diseases 3 and 7 days later. Finally, we surveyed consumers and asked about their opinion and their willingness to pay for bagged fruit.
There were no significant differences in fruit quality between bagged and control (non-bagged) fruit for any of the varieties studied in any of the farms. Thus, bagging did not affect size, mass, sugars or acidity in any of the farms. Bagging significantly increased marketable yield (11%) in the organic farm but did not affect yield in the conventional farm. The increase observed in the organic farm was a consequence of having less fruit damaged by diseases such as brown rot or insects such as plum curculio in bagged fruit compared to control fruit. It is important to highlight that there are not efficacious methods to control these pests in organic farms, and for this reason, bags surrounding the fruit act as a barrier that protect them from pests. However, since non-bagged peaches in the conventional farm are sprayed with very efficacious synthetic chemicals, marketable yield was not improved by bagging in this case (all fruit harvested from both treatments was marketable and did not present any damage). Regarding postharvest, bagged fruit has a shorter shelf life than control fruit, and this is a consequence of not receiving chemical sprays while being bagged. Thus, by day three after harvest, 52% of the bagged fruit showed some damage versus 40% of control fruit. Seven days after harvest, 88% of the bagged fruit was damaged versus 42% of control fruit. In any case, consumer surveys showed that this is a desirable trait for many consumers: fruit with no residues of chemical pesticides. These surveys showed that, when potential consumers were asked to choose which batch of peaches they find more attractive (there were no labels identifying the bagged or the non-bagged fruit) 62% answered conventional, 23% answered they were the same, and 15% answered bagged. When the concept of bagging was explained to the consumer and then asked again what batch they found more attractive 92% answered bagged, 7% answered conventional, and 1% answered they were the same. The most common reason behind the change was because of no chemical residues. The average increase in price that consumers were willing to pay was 38 cents per pound for bagged fruit but this number was very variable depending on where the survey took place (for instance, in a survey at a Farmers Market, many consumers said they were willing to pay up to $1 extra per pound).
The cost of bagging all the fruit (average 400 fruit per mature tree) in a tree is between $14-$17 ($10-$12/h for labor + $4-$5 for the cost of bags). At a premium of $0.38/lb, a mature tree with 400 fruit holds about 250 lb of fruit, that is an increase of revenue of $95/tree, if the grower sells directly to the consumer. Still, there is a good margin for profit even if fruit is sold through a retailer. Thus, if labor is available, this practice can be profitable for growers. In any case, because of the increase in marketable yield seen in organic farms, organic growers may find it even more attractive than conventional growers.
Educational & Outreach Activities
This research and research progress have been showcased through different activities including:
-Field Day (at Musser Fruit Research Farm), where farmers, backyard growers and people with an interest in fruit trees were able to see how this strategy works with a hands-on demonstration in the field by the PI and the graduate student working on this project.
-Five presentations at different meetings: the Southeast Fruit Professional Workers Conference, the Cumberland Shenandoah Fruit Workers Conference, the American Society for Horticultural Science Annual Conference, the Southern Region of the American Society for Horticultural Science Conference, and the Annual Meeting of the Southeastern Branch of the Entomological Society of America.
-One scientific paper is being finalized and will be submitted in June 2017. A few press releases and local news highlighted this research.
-Three Clemson Extension factsheets have been updated and information on fruit bagging (mostly for backyard growers) have been included: Factsheets HGIC 1354 Peaches and Nectarines, HGIC 2209 Peach Diseases, and HGIC 2210 Peach insects and pests.
-About 20 emails/phone calls answered on the use of paper bags, about 20 farmers and 60 agricultural professional involved in outreach and educational activities.
We got very valuable data from this project and we were able to apply and were awarded with a $1M USDA grant (Organic Research and Extension Initiative Program). This new grant was built as a multi-institutional effort, including Clemson University, The University of Florida, and The University of Georgia. Four farmers (two in Florida, one in Georgia and one in South Carolina) are very interested in this strategy and are part of this project. At this point we see there is a very clear market for organic peaches since this is almost nonexistent in this region. This research and this grant has also attracted a lot of media attention and we believe this strategy will contribute to the increase of organic production of peaches in the Southeastern U.S., to the reduction of use of pesticides and fungicides in peach farms, and to the profitability and long-term sustainability of these farms.