Discussion With Dr. Jeremy Pattison About 3 Years of Planting Date and Row Cover Research (9/27/12)
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— Written By Barclay Poling en Español
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Dear Growers, Agents, Agronomists & Others
We have had some delightful weather in this final week of September weather. I has some travel yesterday morning into eastern Wake County (Knightdale), Franklin Coounty, and then finished the day with an additional strawberry farm visit in the Central Piedmont (Greensboro/High Point area). I was happy to see that most growers were planting & irrigating the newly set plugs and fresh dugs (cut-off plants have not yet arrived from CA). Planting continued today under excellent weather conditions for getting the 2012-2013 season underway! I did have an opportunity yesterday morning to also visit a little bit more with Dr. Jeremy Pattison about 3 years worth of research at the Piedmont Research Station (Salisbury) on Camarosa and Chandler planting dates, as well as row covers. Here are some notes from that very informative interview:
My question: JEREMY, WHAT YIELD ADVANTAGE HAVE YOU SEEN FROM PLANTING IN THE 2ND HALF OF SEPTEMBER AT THE PIEDMONT RESEARCH STATION (PRS)?
Dr. Pattison’s reply: “By far, planting date had the most influence on increasing marketable yields. At PRS (planted 9/15, 9/22 and 9/30), we had a 6% reduction between PD 1 and 2 and more concerning was a 26% reduction in yield for 9/22 vs 9/30. These numbers are for Camarosa. It showed me that we need to be on the early side of planting for Camarosa because of that serious yield reduction (5 to 7 days earlier than our “normal” Chandler date). The Chandler data was slightly different over the three planting dates (lost about 8% for PD 1 vs PD 2; 3% reduction for PD 2 vs PD 3). Now, this was a very mild season (2011-2012) and Camarosa out-yielded Chandler in my testing locations except for UMRS. So, I don’t think I would be changing my planting date for Chandler. However, since it was so mild and we saw such a large increase in yield for the window between 9/15 and 9/22 compared to 9/30 (which I think it would have been larger if our weather was closer to normal), I would be trying to set my Camarosa field during that week here in the Piedmont.
My follow-up:Well, I am glad that you do not see a need to change the planting dates for Chandler, but with it now being nearly the end of September, I wonder about the possibility of using a late fall row cover for Camarosa? As you know, a number of growers in the piedmont were forced to delay bed-making and fumigation by a week or more due to rains in early September, and this may delay planting until early October with a 3 week plant-back for the popular fumigant Pic-Chlor 60 ((1,3-Dichloropropene (39.0 %): Chloropicrin (59.6 %))?
Dr. Pattison’s reply: ” As far as the covers are concerned, we are seeing that cooler years/locations will result in larger effects of the covers. So, these numbers will be averaged over all locations so we can “farm the average” with our recommendations. The main effect of covers (averaged over all locations and planting dates) showed that early applications (65 degree trigger)<editor’s note: this refers to an average daily high of 65 F> resulted in a 14% increase in yield compared to the uncovered treatments. When we break out the planting date and look at the row cover by planting date interaction, we see that all planting dates responded positively to early applications and produced an average increase in yield of 16% or 3,000lb/A (the greatest increase was around 20% for the first planting date!). I keep hearing about growers who time their row cover applications for after Christmas. We did December and January application treatments in 2009-10 and 2010-11, and saw no yield increase. If the application strategy is to protect plants from loosing a few leaves during the winter (sanitation) then I guess that’s fine but if they are doing it to increase yield they are spinning their wheels. We will need to stress this during the Expo in the row cover session.” The goal is to: “Farm smarter, not harder”!
Dr. Pattison’s further comment: “The question I had was “how are the covers increasing yield”? It appears that they are increasing flower number per branch crowns as they had NO effect on making more branch crowns. Planting date was the only treatment variable (other than location) that impacted branch crown numbers. This has been consistent over the 3 years of trials. So, the idea that we can look at branch crown numbers in the fall/winter to estimate yield is not that predictive, particularly for Camarosa. Here’s something interesting, in the 2009-10 and 2010-11 seasons (which were colder and had lower yields) we had more branch crowns on Camarosa as compared to this past year. Just looking at the plants we would have said we are in good shape for a high yield. However, I feel that because it was cold, our branch crowns were only “3/4’s loaded”. We can’t rely on last year’s weather having a repeat performance, although my heating bill wouldn’t mind! So, for Camarosa, my feeling is to lean on the early side of planting to get adequate branch crown numbers and then be prepared to pull a cover when temperatures hang consistently around 65-60 degrees to maximize yields. I will also note that the early planting and early cover application did not hurt us on fruit size. We still maintained a very marketable berry weight. My opinion is that our growers can sell an 18 gram berry all day long (although customers might desire a 25g berry) BUT neither of them can sell or eat something they don’t have if yields are low as a result of late planting or cold weather that could have been mitigated by an early cover. One quick note (though), we did have some increased winter blooming as a result of early planting and row cover application. However, it was most pronounced at Castle Hayne and we had very little occur at Piedmont Research Station and none at Upper Mountain Research Station. We need to just be paying attention to what’s going on under there during the early winter to make sure we aren’t forcing the crop during mild weather.
Hope this helps! Let me know if you need anything else.
Dr. Jeremy Pattison
Assistant Professor, Strawberry breeding and genetics, North Carolina State University
Department of Horticultural Science
Plants for Human Health Institute
600 Laureate Way, Kannapolis, NC
Tomorrow we will be discussing questions from the field this week regarding Ridomil Gold application as well as offering some reminders on post-plant fresh dug and plug irrigation
Dr. E. Barclay Poling
Professor Emeritus/Extension Strawberry Specialist & EDITOR
Department of Horticultural Science, NC State University