The subject was discussed on January 15 “Strategic agriculture: let’s talk crops! program
Greeneye technology targeting the application of herbicides directly to weeds. (UMN extension)
ST. PAUL, Minn. — Are you curious about advances in targeted spray technology or wondering if this system could work for you and actually lead to savings? These questions and many others were addressed in the January 15 document “Strategic agriculture: let’s talk crops!” program. Dr. Rodrigo Werle, a weed specialist at the University of Wisconsin-Madison, joined moderator Ryan Miller, UMN Extension Educator – Crops, for a discussion on “targeted spray technology,” highlighting Dr. Werle’s research into this innovative technology.
What is targeted spray technology?
Targeted spray technology is a new system that awaits us. This involves expense, but the intention is to generate savings and other opportunities. Werle’s research team worked with a system (One Smart Spray – Bosch and BASF Digital Farming Joint Venture) already commercially available in Brazil. John Deere markets the “See & Spray” system in the United States and many other companies are currently working on developing targeted spray technology.
Systems that can detect, say, a live weed in a fallow field (called green-on-brown applications) have been around for some time. These systems will spray when something green is detected in a field. In the Upper Midwest, a system that can selectively activate when a green weed is detected in a green crop, or a green-on-green application, might be better suited to our cropping systems.
Cameras installed on the sprayer take images as the sprayer crosses the field. Using artificial intelligence (AI), the system can detect where the crop rank is. If green appears between the rows, this triggers the nozzles to spray. Nozzles turn on and off as weeds are detected. Werle said he expects this to become standard procedure in the future. Premium systems will have two tanks on the sprayer, one for broadcast application and the other for precision spray application where the nozzles turn off when no weeds are present.
These systems can also generate a map of where the product has and has not been applied, as well as a map of weed distribution. Not only can these tell the grower how much he is saving since the area of acres receiving an application is reduced compared to broadcasting a herbicide, but these maps are also useful in showing where weeds are distributed in the field. It is possible to overlay soil maps with weed distribution maps to help determine pre-emergent residual (PRE) herbicide rates during a subsequent growing season, for example, based on the distribution of weed communities and soil characteristics.
A strong early season soil residue program is essential
In tests where acnide was the primary target weed, Werle’s research team led by graduate research assistant Zaim Ugljic found that postemergence foliar herbicide savings (POST) ranged from 70 to 76 % in soybeans when using targeted spray technology where weed pressure was low. However, when weed pressure was high, savings averaged only 2%.
It is important to note that any savings based on a reduction in the amount of herbicide applied are linked to foliar applications. A robust soil residual herbicide program is essential, as the system will be most cost effective where weed infestations are low. If weed infestations are high, the nozzles will rarely turn off and you will essentially be doing a broadcast POST application. This also highlights the importance of keeping weed seed bank levels low.
Interestingly, Werle does not see much benefit in applying another residual herbicide to the soil with a POST application, also known as a layered residual strategy, when a heavy-duty PRE residual herbicide has been applied during the plantation. He finds that in practice, growers are making their POST applications later in the season than would be recommended for the layered approach to work best. This may push the POST application to a time when conditions are generally drier, adversely affecting the effectiveness of the residual soil 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 when it comes to planting.
Economy
Werle demonstrated how moving to a more robust PRE program as well as a POST program consisting of multiple effective herbicide modes of action can come to fruition. It is important to note that you can expect to pay a $5 per acre fee when no herbicide is applied when using the John Deere See & Spray Technology System. These charges only come into play when the nozzles are turned off during an application, not when the unit is spraying. If your herbicide program costs significantly more than $5/acre, using the system should be cost effective in a field with low to intermediate weed populations.
Observe the movement of the jet
Some precision spray systems are configured to activate a single nozzle when a weed is detected. According to Ugljic’s research, even a light wind of 3 to 4 mph can cause the spray to end on the target weed if only one nozzle is activated. When broadcast spraying, the spray patterns overlap to help compensate for this. It is therefore recommended to activate multiple nozzles with your targeted spray technology system when detecting weeds.
Slowing down a bit when creating a POST application with this technology will also increase the accuracy of the system. Currently, a speed between 12 and 15 mph is recommended, with 12 mph being ideal. Keeping speeds low also reduces arrow bounce. Boom bounce changes the distance between the nozzle and the target weed. So, the less boom bounce, the more accurate the application rate and coverage will be.
Complexity is necessary in our weed management systems
As resistance to POST products continues to increase in key weeds like blackthorn, farmers should look to add complexity to their weed management programs. A solid PRE soil residue program is a necessary foundation. Practices such as using a cover crop and planting soybeans in narrow rows to hasten canopy closure can also help. An effective foliar program, with multiple effective modes of action and POST applications on small weeds, is also essential.
For more details, listen to a recording of this program on: z.umn.edu/StrategicFarmingRecordings.
Join us next week!
The University of that of Minnesota “Strategic agriculture: let’s talk crops! » The webinar series, offered Wednesday mornings through March, features discussions with experts to provide up-to-date, research-based information to help farmers and agriculture professionals optimize cropping strategies. crop management. Next week’s session will be recorded LIVE at the MN Ag Expo, focusing on “Sustainable Aviation Fuels,” with Extension Soil Health Specialist Dr. Anna Cates and other industry experts. industry and commodity groups. For more information and to register, visit z.umn.edu/strategic-farming.
Thank you to the Soybean Research and Promotion Council and the Corn Research and Promotion Council for their generous support of this program.
–Liz Stahl, UMN Extension