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MARCH 11, 2020 - UNDERSTANDING HOW TO THRIVE WITH PHYTOGEN BREEDING TRAITS™ FOR RKN

As we get deeper into the 2020 crop planning stages, we will discuss the native breeding trait resistance to RKN and how to best utilize this techonology on the farm.

As March sneaks up on us, we are in full swing of meet and eat season, which has been confirmed by the use of a new hole in my belt loop. Southeast Georgia has looked a lot more like home in West Tennessee over the past few weeks, with a lot of consisent heavy rainfall and many rivers and creeks beginning to run over their banks. While rivers touching the bridge doesn't appear to be as common down this way, I am anxious to see the difference in definition of cresting in the Coastal Plains. 

One topic that is consistent right now, regardless where you are in the world, is the Coronavirus or COVID-19. Thoughts and prayers continue to go out to those impacted during this time of uncertainty, and while we could discuss severity and implications of this epidemic and the timing, it is very apparent how much of an impact this uncertainty is causing on global trade and our commodity markets. As we were already watching pricing closely enough to determine percentage of crop acres to plant in 2020, this epidemic has made planning even more of a challenge. While it appears China is ready to hold up their end of the trade agreement, we must continue to pray this virus is understood and resolved quickly, such that we can see how much basis and futures markets will rebound under the newly signed terms. 

In traveling Central and East Georgia attending county meetings and discussing the PhytoGen® portfolio, the one area garnering more questions is the PhytoGen Breeding Traits™ for root-knot resistance, and believe me, we are probably more excited to talk about this technology than any other in Southeast Georgia. This breeding trait provides resistance to southern root-knot nematode, equally or better than commercial nematicides, is turned on all year for continuous control, and enables significant reductions in populations for the following crop year. It's easy to identify which varieties include the breeding trait by the RKN shield stamped on the variety label as seen below, but also easy to remember in that all of the five key PhytoGen brand W3FE varieties fit for Central and East Georgia contain this resistance package. 



There has certainly been southern root-knot resistant cotton varieties on the market in the past, and with these varieties has come a strong correlation to yield drag when not placed on an acre impacted by RKN. Until now, the bar for RKN resistance was set by DP 1747NR B2XF, as there is no true definition of varying levels of RKN resistance. While the level of control you can expect from the PhytoGen Breeding Trait will meet or exceed that of the limited number of competitive varieties on the market, we are excited to have this trait package in all key varieties moving forward because of the effort to overcome the yield drag. Our breeders have done a phenomonal job of identifying alleles confering resitance through different mechanisms to control root-knot nematode infestations while having minimal impacts on lint yield, and then continously back crossing to achieve consistently high yield in a wide range of maturities. This is evident in PHY 400 W3FE extremely high performance across the cotton belt in university on-farm testing, occuring both in areas with and without RKN populations. 

Now if you are wondering how these traits work on RKN, I'll spare you the hypersensitive responses and alphabet soup and boil it down like this: it stops feeding and breeding. These traits catch RKN in two stages of their life cycle, the first occurs earlier on, once the nematode enters the root and establishes its permanent feeding site, known as giants cells. The gene aids in breaking the handshake amongst the nematode and the cotton root host, thus stopping feeding. The second trait picks up later in the life cycle by reducing egg production in females that have set up shop within the root, thus stops breeding. There are different levels of resistance amongst these key varieties, but again, the level of resistance you can expect within PhytoGen W3FE varieties will meet or exceed the varieties of the past. 

So with little experience and a new shiny tool to manage RKN in Central and East Georgia, how do we place and manage these breeding traits? Per UGA southern RKN thresholds, if your 100 cc soil sample population of southern RKN ranges from 1 - 99 it is recommended to plant a tolerant variety. If RKN is your only nematode pest and you are within this range it becomes very simple, pick your product of choice based on performance, maturity, and other agronomic characteristics, save the $30-40/ac cost on nematicide ($210-240/bag at 7-8 acres/bag) and roll on. If your sample results are 100 or more, it is recomended to use a tolerant variety plus a nematicide, however, this is where PhytoGen Breeding Traits truly stand out against the competition. Many university researchers have acknowledged that PhytoGen Breeding Traits meet or exceed the level of control against RKN in comparison to a nematicide. This is where we could start to make placement and management somewhat complex. 

In the high RKN population sandy soils we have in much of Central and East Georgia, we are more commonly going to find ourselves in the 100 + category, in which multiple integrated pest management strategies can assist us in battling RKN. In these environments, the impact of maturity can certainly come into play as we have seen full maturing, aggressive growing varieties able to overcome the late season stress when the nematicide runs out and provide acceptable yields (cultural control). We also see positive impact from the use of aldicarb, in fighting nematodes, soil diseases, thrips, and providing the famous "carbamate boost" (chemical control). And then there is varietal resistance, which has been limited in the past. Now again, we can get into single gene and dual gene resistance, happy to talk through that, but here is how I would try to best manage placement.

We want to always take an IPM approach to try and get the greatest value out of our investment. Per UGA recommendations for this threshold range, we want multiple methods of fighting this pest. If you are truly pushing for exceptionally high yields, selecting a PhytoGen variety with RKN resistance and then matching with a thrips rate of aldicarb still makes a lot of sense. We get the added benefits of using aldicarb on thrips, possible deer deterrent, etc., but also provide a little extra aid to the in-plant resistance. With the inconsistent and tight market, if we need to save our up front expenses, placing full maturing varieties like PHY 500 and 580 will provide two mechanisms of IPM in extremely highly populated areas. For everywhere in between, the outstanding yield potential and RKN resistance of PHY 400 will help to overcome the pest.

I'll share a little data to illustrate this. The first graph is from the UGA On-Farm Trial at the Sunbelt Ag Expo in Moultrie, GA. Territory Manager Marvin Stewart noticed a major change in the appearance of varieties in the second rep of the trial. Garnering permission, he went and sampled the PhytoGen varieties and neighboring competitors. The blue bars in the graph illustrate the yields across both reps within the trial, the green bars illustrate RKN counts just prior to defoliation from the sampling area in the second rep. The following images are the roots from the subsequent varieties sampled in this trial. When going underground, it becomes very apparent where yield is escaping.



Another example comes from Surrency, GA. This farm has a field history of high RKN populations. Dryland, and mostly droughty in 2019, we never were able to capture RKN populations from our soil samples, but a good picture none the less. The first image you see is the community plot run by a local consultant. This trial had a full rate of aldicarb placed under the seed at planting. In combination with a nematicide, PHY 400 out performed the competition at 1243 lbs/ac. The following graph illustrates yields across the PhytoGen portfolio on the same farm, planted the same day, only separated by a dirt field road and some chicken strips for lunch. However, we didn't use the dry hoppers in the Innovation Trial, giving the trait a true test without the aid of a nematicide. The full maturity and dryland adaptation of PHY 580 was able to overcome the heavy RKN populations and yield equally with PHY 400, the winner of the community plot.




As I close for this month, there should be a lot of reasons to be excited to try PhytoGen in Central and East Georgia for 2020, but none greater than the RKN resistance that will certainly help combat the millions of dollars lost fighting this pest each year across the state. While the global cotton market is up in the air for the immediate future, we have to manage our risks and try to find the most value for our dollar. You have always been able to trust PhytoGen to uniformly emerge on time with exceptional vigor. We are excited to have a portfolio containing PHY 400, 500, and 580, both widely adaptable for consistency, but more importantly excellent fits for our growing environment in the southern coastal plains. 

For more information about cotton production practices in your area, contact your state Extension cotton specialist. As always, your PhytoGen cotton development specialist also is available to discuss agronomic options.

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COTTON DEVELOPMENT SPECIALIST:

SHAWN BUTLER, PH.D.

A native of Jackson, Tennessee, Shawn Butler, Ph.D., is the PhytoGen cotton development specialist for central and eastern Georgia. He holds a doctorate in agronomy and crop science and a master’s in crop pathology, both from the University of Tennessee. While at UT, Shawn specialized in application technology, precision agriculture and remote sensing. He enjoys helping cotton producers find applied solutions and implementing technology to overcome agronomic challenges. When Shawn isn’t scouting fields and visiting with growers, he enjoys following sports, playing golf, boating, and projects around the yard and home.
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