Clemson Extension Upstate District

Advancements in Peach Thinning and Soil Fumigation Techniques

Andy Rollins
Commercial Horticulture Agent
Spartanburg County

Andy Rollins has made significant progress in chemically thinning peaches using ethylene. Ethylene is a naturally occurring gas that increases as many fruits ripen. A common example of its use is placing a ripe banana peel in a paper bag with an unripe tomato, which helps accelerate the tomato’s ripening process.

In commercial peach production, thinning is typically done by hand after the risk of the last frost has passed—generally around April 15th, although this can vary. However, the rapidly rising cost of legal H2A labor, combined with widespread inflation across other farm inputs, has severely eroded profit margins. Many farms are now uncertain whether they can remain operational even for another year.

Rollins has applied ethylene in liquid form to young peach flowers and fruit, which causes the trees to naturally abort a portion of the developing fruit. This spring, he was able to thin 50–60% of the fruit from multiple peach varieties at a cost of just $1.67 per acre (approximately 150 trees), excluding labor for application. In contrast, traditional hand thinning can cost $8–10 per tree. While he encountered some challenges thinning certain varieties, he plans to continue refining the process next year, believing it to be a critical step forward for the future of peach production.

In addition to his work with ethylene, Rollins is also exploring the use of a new biological fumigant applied through an innovative method. Fumigants are essential in commercial agriculture to combat soil-borne diseases, weeds, and pests that can severely damage crops. These substances are highly dangerous, but by using inline injection through irrigation drip tape, exposure to harmful gases is reduced and the fumigant remains concentrated in the soil, where it can effectively target plant pathogens and pests.

This method has gained popularity since Rollins began working with it. He is scheduled to demonstrate the technique at the NC Strawberry Growers Association meeting on November 11, 2025. During the demonstration, he will use blue dye through the irrigation system to simulate the fumigant, highlighting the importance of saturating the entire root zone to ensure maximum efficacy.

Further educational meetings on these practices are currently being planned for early next year.

Farm Gate

Over the past three years, the Clemson Cooperative Extension food crop team has been collecting data for specialty crop production areas and their value to the economy. The pilot scheme began in 2022 with 6 crops. This year marks the repeat of the initial crops and data capture for the remaining 14 crops

Based on the figures for 2024, commercial horticulture in Fairfield County indicates that specialty crops account for $23,310 in revenue. This is based on two years of data, with the final crops to be added this year.

Researchers within the team utilize the data to justify grant proposals; we in Extension can utilize the data to justify our impacts on the state. If you believe or know of any people producing specialty crops in the county, please reach out to me, and I will be happy to collect the information. All information is treated with the strictest confidence.

Rob Last, Commercial Horticulture Agent: rlast@clemson.edu | 803-359-8515 

Spring is in the Air

Rob Last Commercial Horticulture

The days are beginning to warm up with increasing daylight levels to dispel the depths of winter. With the changes in the year, our thoughts as commercial growers or as home gardeners turn to thoughts for the upcoming year.

From either perspective, February is a great time to start vegetable transplants or to sow more cold, hardy crops directly. Of course, while browsing the glossy seed catalogs, it is a good time to review crop rotations and where we had successes or failures.

Commercial Horticulture Resources
A little taste of Spring.
R. Last 2024

For home gardeners, The HGIC factsheet, Planning a Garden, can be a valuable resource for crop rotations, planting times, and depth of planting for seeds.

The South Eastern 2025 Vegetable Crop Handbook is available electronically only.

Some useful commercial fruit and vegetable resources:

MyIpm Apps for both fruit and vegetables are available free of charge from Google Play and the Apple Store.

Also, look into the South Carolina Grower blog and Podcasts where there are a large number of resources, including fruit and vegetable meetings.

Fumigating Strawberries Safely and Effectively

Fumigation lines being run throughout a strawberry field.

Andy Rollins, the Commercial Horticulture Agent for the Upstate, has been working on a project to help growers fumigate the soil more safely and effectively.  This process will help treat and prevent soil-borne diseases and nematodes. In the past growers have used shank type fumigation that involves pulling a plastic bedding machine that has injection shanks in the middle of the bed.  The fumigant is carried on the tractor also and is run through shanks.  Using this method the machine is picked up and put down at the end of every row and lifted in the air.  Workers on the ground assisting are often exposed to fumigant vapors from dripping lines.  Andy is showing growers how to put the gas into the drip system to allow the water to distribute it more efficiently.  This is a closed system with much less exposure for all. Andy has done on-farm demonstrations three times already this year and has three more planned. At Andy’s last demonstration meeting in August growers from at least three states gathered to learn this technique.

Protecting Peaches from Frost & Harvesting Muscadines

Andy Rollins
Upstate Commercial Fruit & Vegetable Agent
Cherokee, Greenville, Spartanburg, Union, & York Counties

Peach Trees
Peach Trees

At the beginning of this year, I continued work with a cellulose nanocrystal particle to verify its ability to frost-protect peach. It was successful but has yet to be commercially available. I spent an inordinate amount of time looking at peach farms devastated by freezing temperatures and writing insurance letters to help support them. I helped start the SCSFGA- South Carolina Small Fruit Growers Association with many farms statewide. This group has formally asked Clemson administrators for Ph.D. assistance with growing small fruits. At this point, asking for funding will go to the state legislature this coming year. This project is excellent for Clemson to participate in, and I look forward to seeing that position develop.

Grapes
Grapes

I am currently harvesting many grape varieties I have planted and maintained. This demonstration aims to expose this farm to newer varieties, which will assist him. We have some wonderful hybrid grape varieties that are smaller than his muscadine. Still, these are seedless and have very high sugar content and thinner skin. One selection of muscadine is Paulk. It will serve as a better pollinator for Supreme, a female muscadine. We have in the past used Granny Val, which is a bronze grape that comes in very late. I want the grower to see the timing of Paulk and how it compares to Supreme. He is looking to involve it in his next planting of Supreme. Lastly, I worked with one farm on a different form of fumigation that is much safer than the traditional method. We will distribute the collected information to all growers at our production meetings and demonstrate it to the NC Strawberry Growers Association in person. I tested the injection method with a donated product and pulled nematode samples from treated and control areas for comparison.

My work with the cellulose nanocrystal particle and grape and muscadine varieties were out-of-the-ordinary projects I worked on this year. I also held production meetings and problem-solved at on-farm visits, as always. I am honored to serve the farmers, growers, and producers of the Upstate.

Upstate Commercial Fruit and Vegetable Updates

Andy Rollins
Upstate Commercial Fruit and Vegetable Agent

Currently, I’m holding all of my yearly production meetings.  At my peach meeting, we had 81 in attendance, with 61 different farms represented.

Along with another agent, we hosted the first meeting of the SC Small Fruit Growers Association.  I assisted Bob Hall in helping to establish the group with representation from across the state.   The production meeting featured a blueberry specialist from out of state, with 50 growers in attendance.

The strawberry production meeting is coming up at the end of February, and the vegetable meeting will be in March.

I will be working on a bloom-thinning product again this year for an on-farm demonstration and I also plan to showcase my on-farm grape work this fall.

On-Farm Grape Trial Yields Coming in Now

Andy Rollins
Upstate Commercial Fruit & Vegetable Agent

Rhazzmatazz with developer, Jeff Bloodworth
Rhazzmatazz with developer, Jeff Bloodworth

An On-Farm planting located at a cooperating farm has established new experimental grape varieties and new muscadine cultivars. Fruit harvest began two weeks ago with ‘Rhazzmatazz,’ a novel seedless hybrid muscadine-vinifera hybrid grape developed by Gardens Alive plant breeder Jeff Bloodworth.

The next grape I just started harvesting is ‘Oh My,’ another seedless cultivar from the same company. Muscadine plants we are evaluating but have not started picking are ‘Paulk’ and ‘Ruby Crisp.’ These are University of Georgia cultivars donated by Dr. Patrick Conner. Other experimental varieties will not begin fruiting till next year as plants were planted one year after initial planting. Yield and quality data on these varieties are being collected for direct farm application. Information from this planting and the demonstration grape farm at Clemson’s Musser Farm assists several new muscadine farmers in the upstate.

Five farmers from several counties toured the Musser Farm to observe small fruit production. More recently, three farmers accompanied me to Gardens Alive Farm in Kings Mountain to consider newer varieties.

Grapes fit well into fall production programs, especially for anyone growing pumpkins and doing Fall field days. We know what works now, but many new varieties are being cultivated. With the information we gather from these trials. We will be ready for what is coming next.

Peach Tree Freeze Protection

Andy Rollins
Upstate Commercial Fruit & Vegetable Agent

I’ve been busy helping several new small-sized farms across the upstate get established and prepare for planting next spring. I have also assisted with a nematode survey of all the upstate peach farms in conjunction with Churimani Kanal, Ph.D., and his graduate student and will continue this work next year.

I am the principal investigator in a trial looking at a frost freeze protection product from Washington State University. It is a cellulose nano-crystal product intended to protect the fruit from freezing temperatures. It has been shown to protect cherry trees from temperatures of 10⁰F to 13⁰F, which could be revolutionary if the technology can be adapted to peach production here in the upstate.

I held a regional blackberry meeting in Savannah, Georgia, with over 50 participants. My peach meeting was on January 22, 2022, and successfully attracted over 50 participants. My strawberry meeting will be on February 24, 2022, and my vegetable meeting will be on March 24, 2022. I have also co-organized a statewide peach meeting held online on March 10, 2022. I am very thankful for all the farms in the upstate counties I serve.