V-C Peanut News Article Jordan Peanut Notes No. 23 2019
For this issue of the V-C Peanut News I will focus on some of the questions we were asked at production meetings this past winter. I will also emphasize some of the key suggestions we made along the way.
I understand the value of increasing pH. Given we might have some zinc issues, whouldn’t we be better off to move pH to 6.5 or higher? Are there any issues with pH at that level? What about micronutrients? The answer is that other than possible increases in Sclerotinia blight, there appears to be no major downside to having a pH of 6.5 or slightly higher. However, on the high plains of Texas where soil pH can be high (but soils are distinctly different than ours in other ways,) growers experienced significant injury from Strongarm when it was first launched. I think we need to shoot for around 6, but if we are higher than 6.2 and approach 6.5 we should be okay. But don’t get above 6.5. With our soils and climate it can be a struggle to maintain a pH around 6.0, and that is where we need to be. If zinc indices are at 250 or higher try to find another field. But for those folks working around modest levels of zinc, a pH of 6.5 can decrease injury potential from zinc.
How about twin rows? Should I transition to that planting pattern? My standard answer is that single rows and twin rows will perform about the same on most soils and in most years (and varieties.) However, in sandy fields the twin row pattern results in greater canopy closure which can shade soils during initial pegging. In addition to optimizing photosynthesis as quickly as possible, fewer early pegs are lost because soils are cooler from shade offered by plants in twin rows. These sandy soils are about the only soils that respond to starter nitrogen fertilizer. Pushing early season growth on hot, sandy soils can help save the early pegs and often promotes earliness with respect to maturity.
What’s the best herbicide to use as a residual with paraquat? Always include Basagran to soften the injury, and while there are some differences between Dual Magnum (and other formulations of Dual), Zidua, Outlook, and Warrant, in most cases in a comprehensive program control is similar among these treatments. With that said, we do rank these herbicides with slight difference in the NC Agricultural Chemicals Manual and 2019 Peanut Information. Take a look at those sources for details, but generally you can get to the same place with all of these herbicides. A reason to consider Zidua, Warrant or Outloook over Dual Magnum early postemergence with paraquat is because you most likely used Dual Magnum at planting. Greater herbicide diversity, even within the same mode of action, can be of value.
How does Sullivan compare with Bailey? Over the past few years I have felt that Sullivan and Bailey are about the same in terms of yield. A lot of data sets demonstrate this but 2018 was different in some of the trials with the official variety testing program in the region. Is Sullivan losing ground or was it ever as good as Bailey? In the early data sets when Sullivan was compared with Bailey, Sullivan seemed to lag a few hundred pounds behind Bailey. But then there seemed to be a period of time when Sullivan and Bailey were on par in just about every comparison I looked at. We will see what happens in 2019, but I still think Sullivan is a good variety and fits an important role for us in the V-C region, especially in the transition to high oleic varieties.
How good are Emery and Baily II? In most of the data sets I have seen Bailey II yields several hundred pounds above Bailey (and everything else.) Hopefully that difference will remain in place as we transition away from Bailey to Bailey II. Emery has also performed well, but depending on what data sets you look at, it does not seem to be that much different than Bailey or Sullivan. I suspect in 2021 or 2022 when we have shifted from Bailey to Bailey II we will be growing significant amounts of Emery, Sullivan and Bailey II. I don’t know that Wynne is going to make it as a substantial variety, and we will need to keep an eye on a new release out of Virginia Tech called Walton. And of course, Jeff (Dunne) will begin making releases and pushing yields in a positive direction.
How do we need to handle leaf spot escapes that seem to be occurring? Barbara, Hillary, and Dan will have good answers to this, but my two cents point to being on time with sprays in a solid program that includes multiple sites of action. This also includes chlorothalonil applied several times either alone or as a complement to other fungicides (don’t forget stem rot) during the season. Alternating sites of action and using effective mixtures will be important if/as we experience greater inconsistency in control with some products. Do everything you can to optimize performance. Barbara has a great section in 2019 Peanut Information that can really help growers be successful in this area.
While I didn’t get many direct questions on tillage, we completed a survey of tillage practices at the county meetings in North Carolina and also at state meetings in South Carolina and Virginia (thanks for filling these out – and I hope the plunger is working well for a few of you!) Reduced tillage in North Carolina was at about 30%. This was an increase from 2014 (about 20%). In 1998, 2004 and 2009 reduced tillage was at about 10, 20, and 40, respectively. We have about 5% using moldboard plow (called braking or flushing, depending on where you are in the state.) In 1998 over 60% of peanut growers were moldboard plowing. The percentage of farmers in South Carolina and Virginia practicing reduced tillage was higher than I expected based on the surveys (approximately 90% and 70% in these respective states.) As we have transitioned to soils that tend to be more conducive to peanut production (sandier land) there is greater flexibility in tillage systems, especially when it comes to efficient digging with minimal pod loss. Also, with an increase in the number of disease management options, most notably effective fungicides, burying residue (our longer rotations help here too) decreases the real or perceived need for deep tillage. In several instances at the meetings farmers indicated that they thought moldboard plowing would have increased significantly due to weed issues (primarily Palmer amaranth) and the need to bury those seed. That did not turn out to be the case based on the survey.
Is sweetpotato a good rotation for peanut? Yes, it seems to be a good crop to have in sequence with peanut. How about the guava root knot nematode? Right now most experts feel confident that peanuts are not an effective host for this nematode. That is a good thing and we hope this turns out to be the case for sure – fewer hosts for a pest are almost always better.
I’m on 30-inch rows; do I still need to have 5 plants per foot of row? Yes, the difference in 30 and 36 inches is not huge, and the in-row population needs to be the same for both. If peanuts were planted in narrower rows, say 15 or 20 inches, would the answer be the same? My answer to that is based on work we did over a decade ago when we compared single rows, twin rows and a configuration I called narrow twin rows (dropping in between two regular sets of twins on 36 inch rows with another twin-row unit.) In that work we found that the standard twin row pattern did better in some instances than a standard single row pattern, but in all cases the narrow twin row pattern did no better than single or twin rows. Planting in 30-inch rows does allow one to match equipment for all crops on their farm. But from what I have seen there will be no difference in yield with 30-inch rows compared with 36-inch single or twin rows. Narrower rows and twin rows are more expensive based on seed cost (narrower rows and in some cases twin rows) and insecticide and inoculant costs (per acre).
Should I be using Apogee? With more than half of the growers in North Carolina and Virginia using this product it is clear that there is value at the farm level (farmers generally do not waste money.) Since I started in this position in 1996 research with Apogee (at one point called Baseline) has been a consistent element of our research plots each year. In the early days when we were growing NC 7 and then NC-V 11, NC 12C and Perry, we used to get significant and predictable increases in yield in many cases. In recent years, primarily with Bailey, results from small-plot trials often point to little or no yield benefit. I’m becoming more and more convinced that the lack of demonstrating a yield response in small plots may be related to how we conduct the trials compared with results from larger plots with growers. Scott Monfort at UGA and a group of specialists across the peanut belt are summarizing work with lower rates of Apogee (along with the suggested use rate) and it is fairly clear from those data that a positive yield response to Apogee was noted in large-scale farmer trials but seldom in small-plot research. There are a number of reasons why this could be the case (I’ll discuss that later this summer on our NC State Extension portal when there is more room to do so and the discussion us more timely.) Apogee is still expensive but there appears to be value to using it. When it comes to rate, I’m still a believer in using the manufacturer’s suggested use rate and number of applications recommended on the label. But a parallel to Apogee is using mepiquat chloride in cotton. Growers have a number of ways they approach rates and timings and total number of applications, and I think this is becoming the norm in peanuts as well.
Of course Barbara and I discussed resistance management across pests in significant detail. Being timely with practices and diverse (sites of action) and keeping the resistant elements (biotype is one way to describe the individuals in the total population that tend to be resistant) from reproducing and becoming the dominant individuals in the population is important. We do this by decreasing selection pressure, which is mainly caused by using pesticides with the same mode of action far too frequently. Chemistry rotation is extremely important to protect our pesticides as important resources for use in peanuts.
Better stop here. There were several other questions along the way but space is limited. We often post answers to questions we receive during the summer on our NC State Extension portal. You can sign up for that and get e-mail reminders throughout the season.