By Liz Stahl
Are you curious about advances in targeted spray technology, or wondering if this system could work for you and actually lead to cost savings? These questions and more were addressed in the January 15 “Strategic Farming: Let’s Talk Crops!” program. Dr. Rodrigo Werle, Weed Scientist with University of Wisconsin-Madison, joined moderator Ryan Miller, UMN Extension Educator - Crops, for a discussion on “Targeted Spray Technology,” highlighting Dr. Werle’s research around this innovative technology.
What is targeted spray technology?
Targeted spray technology is a novel system that is coming our way. There are expenses involved, but the intent is to generate bottom-line savings and other opportunities. Werle’s research team has been working with a system (One Smart Spray – Bosch and BASF Digital Farming Joint Venture) that is already commercially available in Brazil. John Deere is commercializing the “See & Spray” system in the U.S. and there are many other companies currently working on the development of targeted spray technology.
Systems that can detect, for example, a living weed in a fallow field (a.k.a. green-on-brown applications), have been around for a while. These systems will spray when something green is detected in a field. In the Upper Midwest, a system that can selectively turn on when a green weed is detected in a green crop, or green-on-green application, could be a better fit for our cropping systems.
Cameras on the sprayer take images as the sprayer goes through the field. Using artificial intelligence (AI), the system can detect where the crop row is. If green is seen between the rows, this triggers the nozzles to spray. Nozzles go on and off as weeds are detected. Werle commented that he expects this to be the standard procedure in the future. Premium systems will have two tanks on the sprayer, one for a broadcast application and the other for precision spray application where nozzles turn off when no weeds are present.
These systems also can generate a map of where product was applied and where it was not and a map of weed distribution. These can not only tell a producer how much they are saving as the amount of acres receiving an application is reduced compared to broadcasting a herbicide, but these maps also provide value in showing where weeds are distributed in the field. There is potential to overlay soils maps with weed distribution maps to help determine preemergence residual (PRE) herbicide rates in a subsequent growing season, for example, based on weed community distribution and soil characteristics.
A robust early-season soil residual program is key
In tests where waterhemp was the key target weed, Werle’s research team led by graduate research assistant Zaim Ugljic found that postemergence (POST) foliar herbicide savings ranged from 70 to 76% in soybean when using targeted spray technology where weed pressures were low. When weed pressure was high, however, the savings averaged only 2%.
It is important to note that any savings based on a reduction in the amount of herbicides applied are related to foliar applications. A robust soil residual herbicide program is key since the system will pay off most where weed infestations are low. If weed infestations are high, the nozzles will rarely turn off and you will essentially be making a broadcast POST application. This also emphasizes the importance of keeping weed seedbank levels low.
Interestingly, Werle is not seeing much of an advantage to applying another soil residual herbicide with a POST application, also known as layered residual strategy, when a robust PRE residual herbicide was applied at planting. He is finding that in practice, growers have been making their POST applications later in the season than would be recommended for the layered approach to work best. This can push the POST application into a time where conditions are typically dryer too, hindering effectiveness of the soil residual product (e.g., Dual II Magnum, Warrant, Outlook, Zidua). As a result, he is a strong proponent of starting with the most robust PRE residual program around planting.
Economics
Werle demonstrated how a shift to a more robust PRE program along with a POST program consisting of multiple effective herbicide modes of action can pencil out. It is important to note that you can expect to pay a fee of $5 dollars per acre where no herbicides are applied when using the John Deere See & Spray technology system. These fees only kick in when the nozzles are off during an application, not when the unit is spraying. If your herbicide program costs significantly more than $5/acre, there should be a return for using the system in a field with weed populations are low or even intermediate.
Watch spray displacement
Some precision spray systems are set to only activate one nozzle when a weed is detected. Even a slight wind of 3 to 4 mph can result in the spray ending up off the target weed if only one nozzle is activated according to research by Ugljic. When broadcast spraying, nozzle spray patterns overlap to help compensate for this, so it is recommended to activate multiple nozzles with your targeted spray technology system upon weed detection.
Slowing down a bit when making a POST application with this technology will increase the precision of the system as well. Currently, between 12 to 15 mph is recommended, with 12 mph being ideal. Keeping speeds down also reduces boom bounce. Boom bounce changes the distance the nozzle is from a target weed, so the less boom bounce there is, the more accurate the application rate and coverage will be.
Complexity is needed in our weed management systems
As resistance to POST products continues to increase in key weeds like waterhemp, farmers need to be looking to add more complexity to their weed management programs. A robust soil residual PRE program is a needed foundation. Practices such as using a cover crop and planting soybeans in narrow rows to speed up canopy closure, can also help. An effective foliar program, with multiple effective modes of action and POST applications to small weeds, is also key.
For more details, listen to a recording of this program at: z.umn.edu/StrategicFarmingRecordings.
Join us next week!
The University of Minnesota’s “Strategic Farming: Let’s talk crops!” webinar series, offered Wednesday mornings through March, features discussions with the experts to provide up-to-date, research-based information to help farmers and ag professionals optimize crop management strategies. Next week’s session will be recorded LIVE at the MN Ag Expo, focusing on “Sustainable Aviation Fuels”, with Dr. Anna Cates, Extension soil health specialist, and other industry and commodity group experts. For more information and to register, visit z.umn.edu/strategic-farming.
Source : umn.edu