Increased Workload during COVID-19 – Andy Rollins

February 1, 2021

My workload during this past year has increased substantially compared with 21 other years of service.  I will attempt to share the high points of what I was able to accomplish during this time.

Chart

One of the major projects I worked on this year was to work on a grant that was funded through the SC Peach Council entitled “Evaluate Effectiveness of UV/Sun Protectants Use on Peaches.”  This was a major amount of work in and of itself.  Bacterial Spot was found in many of our late peach varieties across the entire upstate peach growing region in 2019.  We had significant problems in Jersey Queen, Flameprince, BigRed, Ohenry, September Sun and September Sweet.  In some cases, entire blocks of peaches could not be sold because of this problem.  There were varying degrees of damage even on the same variety on different farms.  One of the interesting findings is that on all farms the disease was only found on the portions of the peaches receiving direct sunlight.  These were the furthest fruit from the centers of the tree on the outer reaches.  This would have been the same fruit to receive the most amount of bactericides and the highest amount of drying conditions from wind.  Bacterial problems normally prefer longer amounts of wetness for infection to occur.  This has led me to believe that there is another factor that is not currently being evaluated by other researchers.  The ultraviolet portion of the sunlight can and does cause damage to plants as well as to people.  There is no doubt that the sun and or related heat is causing this damage.  What we don’t know is the efficacy of the products sold specifically for this purpose or if the base components of these products mainly Calcium can achieve the same result at a lower cost.  I tested two of the commercially available products sold for the sole purpose of preventing sun damage to peach (SunShield ‘organic/OMRI product and Reflections (Miller Chemical Co.).  Both are sold and can be bought commercially for sunscald.  I tested these products against two readily available powdered generic products that are not directly labeled for being used in this way.  Both other two products are legally allowed to be used in the production of peaches.  They just aren’t specifically labeled for helping you with sunscalding issues.  The reason for testing these two products was to provide a cost saving alternative in that these products will need to be used many times in order to adequately protect the fruit.  One of those products is Diamond K gypsum.  It is an easily dissolvable form of calcium and the other is just hydrated lime.  Hydrated lime was used throughout the entire production of peaches in the 1940’s and can surprisingly still be used and can help with other issues also.  There were 4 treatments (Sunshield, Reflections, DiamondK Gypsum, and hydrated lime) tested and a control.  I had at least 10 trees per treatment and 50 trees per replication.  I had 3 full replications for a total of 150 trees tested.  Sprays began at shuck off and continued till harvest.  Postharvest attributes were assessed as well as the percentage of peaches found with any bacterial spot as compared to those free of the disease.  Also, attention was given to the portion of the fruit where the disease is found and the relative percentage of the fruit that has been damaged.  Preliminary results were taken soon after first symptoms of the disease arrived. The results are below.

This information was statistically analyzed by Dr. Guido Schnabel.  orange A 3.3303656, yellow A 3.1340126, white B 2.4020437, pink B 2.3990123, blue B 2.3594686.  The control and sunshield (orange and yellow) had significantly more disease than the other three treatments.  So hydrated lime, reflection, and calcium had some effect (but still lots of disease).  This early result gave reason to continue in full force.  All treatments were applied every two weeks all the way through the summer as planned.  A force of summer interns from Clemson university and Musser Farm workers were critical in the final assessment at the end of August.  The fruit and leaf disease portions of this disease had progressed significantly.  A virus Prunus Necrotic Ringspot Virus (PNRSV) was found in these trees and it was learned that it could be making the trees more susceptible to the bacterial disease.  Further work in this regard is planned by Clemson specialists.  We were able to finish all the data collection, but the final analysis and report has not been completed.  We are also waiting on leaf and fruit samples to be analyzed by Dr. Juan Carlos Melgar.

Picture 1

Early blooms

I was also able to test out a new botanical omri (organically) approved botanical fungicide for use on peach for blossom blight.  I was able to perform two tests of this product on farm to see its effectiveness. I was able to test it at Glory Farms in York County, SC on Downy Mildew of several leafy greens and this was under a protective structure. I was also able to test it on Blossom blight of peach at peach farm near Chesnee, SC. Neither test was randomized. I will summarize my findings separately.  Glory Farms is an organic farm and had a problem in their spinach greens but upon investigating it was downy mildew and the disease was widely spread throughout multiple greens varieties and species and throughout the entire protected house. The disease was progressing rapidly. There weren’t many options for her organically and I wasn’t sure what I was going to recommend.  I remembered that I had the new product you had told me of EcoSwing but I had not considered it because my plans were to use it for peach.  After speaking with the company representatives, it was labeled and worth giving it a try even though this was more of a “rescue” kind of situation at that point.  On March 6, 2020 I sprayed the product myself on 4 rows of greens.  There were 2 rows of spinach 1 ½ rows of Arugula, and ½ row of Mustard. I mixed the product at a rate of 1 fl.oz./gallon of water and sprayed each 40-foot row with 1 gallon of product. In the worst areas on each row I made sure to leave a small 3-foot area of row unsprayed to be able to see the difference between sprayed and unsprayed easily. I had the grower inspect the plants for the next two days after application and there was no foliar damage from applying the product even though I had applied during the hottest part of the day. After 2 weeks, I returned to assess the results. I found that product was able to control this disease. My controls were destroyed with very few plants remaining in those entire blocks, but my treated areas were fully intact albeit the disease was not completely eradicated. I should have had actual stand counts before and after to better show this more accurately, but I only did estimates of % of full stand.  Spinach before treatment was estimated at 75% of a stand and 2 weeks later still retained 75% of a stand or possibly slightly higher. The Arugula and the mustard were in similar situations but started with slightly higher stands 85% and finishing with 85%. The untreated controls for spinach started with the 75% but ended up with less than 10% as did the arugula and mustard went from 85% down to less than 10% of a stand 2 weeks after application.

I also tested EcoSwing in the bloom of CaroKing variety peaches. The grower in this case sprayed twice with product during bloom.  I evaluated the bloom by taking bloom counts between the control and the treated row.  Unfortunately, the disease pressure was very low and, unknown to me at the time, I did not have a true untreated control. I had trees that had EcoSwing being compared to trees that had Bravo applied at the same interval. On each branch I just looked at the number of surviving blooms/fruits versus number total number of flowers present to try and compare. I was not able to find anything that I knew for sure was blossom blight, so this was an attempt to see if there were any differences between the two treatments. There were none.  The Bravo treated trees and the EcoSwing trees both had nearly identical numbers of surviving flower/fruit. Cold damage had also hurt this crop as well. It is a little more bud tender than many. Assessment was done on March 20th. Picture 1 shows one of the shoots I would take data on counting number of live flowers/fruits to total number of flowers/fruits per shoot.  I still have some product left over that was not used. Hopefully, this coming year I will have more time to plan a small protocol for evaluating it on peach or possibly strawberry.  I am thankful I now know more about this product and what it can do.

We found no significant differences between treatments even though there appeared to be a higher fruit load on the AKX-835 treatment.  The grower estimated only ½ bu per tree in the AKX-234 and 2 ½ bu per tree in the AKX-835 and the control treatment.  The control treatment was badly selected as it was an outside row receiving more sunlight which was exaggerated because the trees were planted in east to west orientation.  The control trees also bloomed about 1 week later than the rest of the block of trees.  I am glad I did this work with the assistance of the grower.  Further examination is planned for next year.

Planted on farm muscadine trial with novel true seedless plants developed from Gardens Alive Nursery and some plants from the breeding program at the University of Georgia, Dr. Patrick Conner’s program on a large muscadine farm near Inman, SC.  The purpose of establishing this test site was to expose the significantly sized grower some other options that are available to him.  I also plan on doing demonstrations on this site in the future and including other novel varieties that I receive from breeding programs that show promise.  This year’s work amounted to planting and multiple visits to prune, tie/train, fertilize and spray if needed to take care of these plants.  Many of these plants have reached the top wire and are now developing the cordons.  Some fruit data will be available next year.  Also, with the help of a master gardener volunteer we were able to take diameter measurements at planting.  I will measure them again this winter to get a measure of how much each of them grew this year.  Bloom, fruit yield and fruit quality will all be measured next year.

Insect monitoring paid off in assisting all the peach growers in the Chesnee area with critical information on whether their sprays were controlling a fruit worm that had done significant damage in previous years.  With the information we were able to provide we were able to save growers and the environment from ineffective sprays.  We also helped make recommendations as to rotations of insecticides that would be helpful for controlling this pest.

I remained vigilant this year on assisting growers with there on farm needs related to insect and disease problems as well as weed control problems and the like.   I am currently assisting many growers with planting of strawberry plants.  We have 1 new grower in the area and many others who have never used the type of plant they are having to use this year directly because of problems with getting strawberry plants due to COVID outbreaks in the strawberry plant growing regions.  It was a very different year but a very successful year for many of the farms.  Thank you so much for your continued support of Clemson Extension Service!