Using Precision Agriculture to Manage Nematodes in Brazil

Nematodes in cotton
Typical spatial distribution of nematodes in cotton characterized by the presence of circular and oval-shaped infected spots.

As promised in my first article, this month I am writing about some technical aspects related to the use of precision farming tools for the site specific management of nematodes, with a focus on cotton.

Phytopathogenic nematodes are among the main factors limiting the achievement of higher yields in the Brazilian Cerrado. Failure to adopt adequate management practices allows nematode populations to reach very high levels, causing yield losses that can exceed 50%. In the soybeans-cotton crop sequence, the more important nematodes are the soybean cyst nematode (Heterodera glycines) and the root-knot nematode (Meloidogyne incognita). The identification of these species can be done by observing the symptoms in the roots, but the laboratory analysis is important to confirm the diagnosis and to estimate the population levels of each species.

Once introduced in an area, it becomes very difficult to eradicate a nematode problem, and it is necessary to adopt practices of population reduction and minimization of potential damages. The most important practice is the use of resistant or tolerant crop cultivars. In the case of tolerant cultivars, it is important that the populations of the nematode are below some threshold, otherwise it must be associated with other control techniques, such as the use of nematicides in the seeding furrow.

The spatial distribution of nematodes is characterized by the presence of circular or oval-shaped infected spots, with marked spatial and temporal variability. The existence of these spots is related to the low mobility capacity of nematodes, which is a few meters in a year, unless they are transported by some disseminating agent, such as agricultural machines. However, temporal variability occurs because plants submitted to a high initial population may have reduced root growth, reducing the supply of food to the nematodes in that place and thus reducing the final population. Places with an intermediate population allow better establishment of the crop, greater supply of food and with that greater nematode population. This makes the spots with larger populations vary from one place to another in each season.

Typically, the problem starts as few and small spots in a field, but the use of susceptible cultivars can result in high nematode populations in a few years. Because of that, the early diagnosis of the problem and the adoption of practices to avoid greater losses is of great importance. This can mean adopting a particular practice across the whole area when only 5 or 10% of the field actually has problems.

Due to these facts, the above mentioned control tools — genetics and nematicides — represent opportunities for the use of precision agriculture, either as localized practices or through variable rate application.

The main limitation for adopting precision farming tools for nematode management is the difficulty of accurately mapping the spatial distribution of nematodes. In general the nugget effect is high and the range of spatial dependence is short, which requires large numbers of samples to perform a good characterization of the spatial distribution. In addition, the observation of temporal variability makes it necessary to identify the population of nematodes present in the area at a time close to sowing, since the most important information for decision making regarding the control methods to be used is the population of nematodes that may affect the crop in its initial development.

The collection of samples of roots and soil in high density for sending to the laboratory can be cost prohibitive, and alternative methods are necessary to represent the distribution of nematodes with the appropriate resolution level. Remote sensing, mainly with the use of multispectral images of high resolution, is one of the techniques that has been used. For this, it it is necessary to assume that high populations of the nematode cause a significant reduction of the biomass of the crop, which allows the use of vegetation indexes that present a good correlation with the biomass to indicate places with greater probability of occurrence of nematodes. The main limitations of this tool are related to the fact that other operational or phytosanitary problems can also cause the reduction of plant development in a similar way, and it is difficult to differentiate the cause of the variability. There is also the possibility that the nematodes are causing yield loss without biomass reduction. Thus, it is important the use of images is associated with field scouting to verify the relationship of low development areas with high nematode populations.

In this sense, the use of hyperspectral sensors associated with novel techniques of data analysis can allow the differentiation of the causes of variability and to isolate the sites with nematode problems with greater accuracy. While this does not become reality, the strategy that has been used is the use of images associated with dense field verification and the collection of some samples for laboratory confirmation. Field scouting uses a scale of symptom notes and rely on good people training so that the visual interpretation is well calibrated.

Once the spatial distribution of the nematodes is mapped, one can optimize the available control tools according to the risk of damage to the next crop. From a genetic point of view, varieties with resistance or greater tolerance to a certain species of nematode may have lower yield potential than another similar cultivar that is susceptible. Thus, it would be possible to use a cultivar with greater tolerance or resistance only in nematode-infested sites, and to use susceptible varieties in areas without the presence of the nematode. This practice, however, requires the availability of specialized equipment, such as a sowing machine capable of changing varieties in real-time.

The control with the use of chemical nematicides in the seeding furrow can be done locally and also at variable rates. Localized application will be done only in areas where the nematode population exceeds a certain limit. Variable rate application is based on the fact that the protection time provided by the nematicides is proportional to the application rate, and the tolerance of the plant to the nematodes increases as the size of the root system increases, by a dilution effect of the nematodes. Thus, higher doses are used in sites with larger populations of nematodes to protect plants for a longer period of time until they are able to support nematodes that are not controlled by nematicides. For this type of application, the necessary equipment is readily available in most farms.

The cost of a nematicide application in the seeding furrow for cotton crops is around US$150 per hectare, which represents around 6% of the production cost of the crop. With variable rate application, reductions of 40% in the volume of nematicide applied have been observed, mainly in the areas of a field where the nematodes are not yet present and the product does not need to be applied. The yield of cotton in the areas where this technology has been adopted has been equivalent or greater than in areas with flat rate application.

After two years developing this technology, we conclude that the tools for surveying variability need to evolve, but there are great possibilities for expanding its use, since the technique has proven to be viable. Considering the typical case, the investment of US$10 per hectare for the mapping of the spatial distribution of the nematodes can provide US$60 per hectare of savings in the amount of nematicide used, obtaining the same cotton yield. In addition to the US$50 benefit per hectare, the use of the site-specific application brings an environmental gain not yet quantified, since the nematicides used are highly toxic and its application in places where it is not necessary can contribute to the elimination of other organisms and cause biological imbalances.


Leave a Reply

Americas Stories
AmericasIPNI Brazil: Precision Agriculture to Improve Nutrient Use Efficiency
October 16, 2017
As I mentioned in my last article, the IPNI Brazil Symposium on Precision Agriculture was held in early October in Read More
APSUL overview
AmericasFuture of Digital Agriculture Arrives at South American Precision Ag Event
October 2, 2017
Last week I attended the fourth South American Congress of Precision Agriculture and Precision Machinery (IV APSUL America 2017). The Read More
AmericasThe Planting Revolution in Brazil
September 27, 2017
While I currently work independently in the area of agricultural technology, I also participated in all of the development of Read More
AmericasUsing Precision Agriculture to Control Herbicide-Resistant Weeds in Brazil
July 24, 2017
The occurrence of weeds in agricultural fields of grain and fiber production has caused losses to farmers for a long Read More
Trending Articles
AmericasIPNI Brazil: Precision Agriculture to Improve Nutrient Use Efficiency
October 16, 2017
As I mentioned in my last article, the IPNI Brazil Symposium on Precision Agriculture was held in early October in Read More
Decision Support SoftwareFarmers Edge, Service Provider Talk High-Frequency Imagery Deal
October 11, 2017
As the domestic ag tech market continues to mature and develop as we barrel into 2018, another intriguing partnership has Read More
Corn Field Sunset
Industry NewsEFC Systems’ FieldAlytics Now Available in Canada
September 29, 2017
According to an AgPR news release, FieldAlytics is now available in Canada through FieldAlytics Solutions Canada, Inc. This new company Read More
Decision Support SoftwareSciFi in Ag: Chatbot with your Plants?
September 26, 2017
(Article Notes: This monthly column takes some crazy sounding ideas and applies them to the field of Ag Tech. The Read More
Robotics/Labor SaversDeepfield Robotics to Showcase Precision Agriculture Technology at Agrilevante
September 22, 2017
Deepfield Robotics is preparing to showcase its robotics and automation technologies for the agriculture market at the Agrilevante event, in Read More
Farmer with iPad
Australia/New ZealandAgrian Expands into Australia
September 20, 2017
In line with a familiar growth trajectory, Agrian Inc. is moving into Australia with a physical support and sales presence Read More
Latest News
Specialty CropsOpinion: Agriculture’s Big Data is Coming to You
October 20, 2017
If you think your world is changing at a dizzying pace, you ain’t seen nothin’ yet. That’s my takeaway from Read More
Ohio State
Data ManagementRecap: The Ohio State University Explores Ag Tech ROI a…
October 19, 2017
How do soybean producers begin to extract value from the vast selection of digital tools available in agriculture today? At Read More
Industry NewsAGCO, Climate Corp. Announce Digital Partnership
October 19, 2017
AGCO announced today a new digital partnership with The Climate Corp. that will provide AGCO customers the option to connect Read More
Industry NewsFieldReveal Inks Agreement with Texas Agronomy Outfit
October 19, 2017
FieldReveal has entered into an agreement with Ag Producers Cooperative of Dalhart, TX, to offer the full FieldReveal precision ag Read More
corn weather
Data ManagementSeasonal Weather Outlooks: High Risk Worth the Reward?
October 18, 2017
Often, when discussing weather service needs with a potential client, I am asked about the possibility of providing long-range weather Read More
Industry NewsAgDNA Announces Dealership Expansion
October 18, 2017
This week AgDNA surpassed their growth projections, announcing partnerships with eight new multi-store dealerships across the mid-west, mid-south and east Read More
AsiaIndia Maps 185 Districts Through Remote Sensing for Hor…
October 17, 2017
India’s Union Ministry of Agriculture has mapped 185 districts under a project using remote sensing technology to identify areas best Read More
AmericasIPNI Brazil: Precision Agriculture to Improve Nutrient …
October 16, 2017
As I mentioned in my last article, the IPNI Brazil Symposium on Precision Agriculture was held in early October in Read More
Data ManagementUsing Vector Soil Data in a Raster World?
October 16, 2017
Why spend the time and resources to extract the NRCS ‘Soil SURvey GeOgraphic’ (SSURGO) soil polygons only to display the Read More
Precision Irrigation
Precision Irrigation4 Important Ways Precision Technology Is Impacting Irri…
October 12, 2017
Water management is becoming an increasing concern in agriculture, whether that’s dealing with too much or too little water. This Read More
DronesDroneLife: Global Ag Drone Industry Potentially Worth $…
October 12, 2017
Via’s Jason Reagan: According to an August study by Esticast Research & Consulting Market Research, the global commercial drone Read More
Decision Support SoftwareFarmers Edge, Service Provider Talk High-Frequency Imag…
October 11, 2017
As the domestic ag tech market continues to mature and develop as we barrel into 2018, another intriguing partnership has Read More
Planet Labs satellite imagery
Industry NewsFarmers Edge, Planet Labs Announce Multi-Year Exclusive…
October 11, 2017
Farmers Edge announced today a strategic partnership to bring Planet’s best-in-class global monitoring platform to the Farmers Edge precision agriculture Read More
John Deere Combine Harvester at Hagen Farms
Decision Support SoftwareAg and Rail Equipment Uptime Critical for Good Harvest
October 9, 2017
Across the American Heartland, growers have started harvesting their crops for what the USDA predicts will be a good yield Read More
Ag Drone
Industry NewsBotlink, SST Announce Integration
October 6, 2017
Botlink has announced a seamless flow of actionable aerial data into the agX Platform. This integration makes it quick and Read More
corn field
Industry NewsEFC Purchases AgSolver Assets, Establishes New Sustaina…
October 6, 2017
EFC Systems announced it has purchased the assets of AgSolver Inc. The move establishes a new Agronomic Planning and Sustainabilty Read More
Ag Retailer and Grower WinField United
Australia/New ZealandNew Technologies vs. Agronomic Knowledge in Precision A…
October 4, 2017
As the days are getting longer and the temperature is starting to rise, Australian broadacre growers are gearing up for Read More
Field Sky Beauty shot
Industry NewsClimate, West Central Distribution Join Forces on Phosp…
October 3, 2017
To help farmers improve productivity and return on their investment, West Central Distribution and The Climate Corporation have teamed up Read More