The Council for Agricultural Science and Technology (CAST) regularly publishes issue papers on topics that are important to agriculture.

In Apr. 2017, CAST published Issue Paper No. 58 entitled “Crop Protection Contributions toward Agricultural Productivity”. This paper’s contents cover the past, present, and expected/needed future developments of crop protection products and strategies and how they have and will continue to play a major role in the quest for greater food productivity and food production security. Summary highlights of portions of this article as related to soybean production in the Midsouth follow.

General

The current plant protection issue is driven by the realities of pesticide resistance, market forces, and real or perceived ancillary effects of pesticide use.

The automatic use of crop protection chemicals is no longer efficacious or justifiable.

Genetic techniques likely will fit into integrated systems of pest control. However, resistance management plans are essential for all pest control efforts that involve pesticides.

Scientists from all pest management disciplines must strive for improved communication and cooperative efforts to develop integrated strategies for pest management.

Increased crop productivity requires adequate crop protection because the potential increase in yields is often associated with increased pest pressure that will jeopardize the potentially greater yields.

The cornerstone of Integrated Pest Management (IPM) strategies is the exclusion of yield-reducing pests; i.e., pest excluding actions and maintaining a production environment that will not support establishment of pests or will lessen their impact.

Advanced diagnoses based on monitoring that will lead to rapid pest detection and identification will enhance IPM tactics to increase pest exclusion.

Plant Protection Trends–Current and Future

Plant Pathogens and Fungicides.

•     The last group of compounds released with a novel MOA was the strobilurins in 1996.

•     Since that time, new releases of commercial fungicide products have been combinations of previously known active compounds with known and limited MOA’s.

•     The high reliance on only a few fungicide groups with limited MOA’s to apply to major commodity field crops has led to documented widespread resistance in soybean pathogens (See Final Report for MSPB Project No. 61-2015).

Insect Management and Insecticides.

•     Selectivity is increasingly important regarding insecticides; they should be selected based on minimal impacts on non-targeted species such as beneficials, pollinators, humans and other mammals, and the environment.

•     Only a limited set of new insecticide materials represent new IRAC groups of chemistry.

Weed Management with Herbicides.

•     No herbicides with new or novel MOA’s have been introduced into the field crop market in over 30 years.

•     The availability of HR crops in the mid-1990's brought about a new approach to weed control in crops, resulting in simpler control strategies and expansion of conservation tillage systems.

•     The advent of HR weeds highlights the urgent need for new weed control technologies that can be used in large-scale farming systems.

•     The increasing resistance of weeds to present-day herbicide MOA’s also highlights the urgent need for new herbicide MOA’s.

•     New herbicide discovery is hampered by the high cost of their development and approval, and their uncertain long-term revenue potential because of defined patent lifetime, generic herbicides, and selection for HR weeds in cropping systems where they will be used.

New Biological Insect, Disease, and Weed Management Tools

•     Biological control of plant pathogens must be explored for new tools that will enhance the sustainability of agricultural production.

•     Long-term cropping systems studies must be given funding priority to ensure enough time is allotted to explore and determine/develop crop-specific biological control solutions.

•     Biological and microbial pesticides are gaining in popularity since it is perceived that they have a decreased environmental impact compared to conventional synthetic pesticides.

•     Development and regulatory approval of biopesticides generally require less time and expense than for synthetic pesticides.

•     Very few bioherbicides have been commercialized. Production and formulation technologies, the inherently restricted weed control spectrum, and environment-dependent efficacy all limit commercialization potential. (See the Allelopathy White Paper on this website for more detail.)

•     Rapid identification of natural biocontrol products and genetic manipulation of these products should enhance their development.

Seed Treatment Technology–Benefits and Costs.

•     Many of the materials used in seed treatment products are insoluble in water. However, compounds in the neonicotinoid insecticide class are soluble in water; therefore, seed can be treated with materials in this class and the material will be translocated from the roots into the plant shoots and leaves, thus becoming plant-incorporated protectants (PIP).

•     Two neonicotinoid insecticide active ingredients–thiamethoxam and clothianidin–have been routinely used as seed treatments.

•     New formulation technologies will allow more seed-applied insecticide materials to be used as PIP’s.

•     From 2008 to 2012, neonicotinoid seed treatments were used on about 30% or 71 million acres of soybean. By 2013, approximately 75% of soybean seeds were treated, usually with both a fungicide and insecticide.

•     Insecticidal seed treatment costs for soybean can vary from $7 to $14/acre.

•     Use of seed treatments in low-to-moderate pest pressure situations indicates that their use and need are not necessarily correlated. (It is noted that fungicide seed treatment use in Midsouth soybean systems has been and is a worthwhile risk-avoidance practice, especially in environments that increase the probability of a failed stand and because of their low cost).

•     The ability of soybean cyst nematode (SCN) to overcome SCN resistance management practices such as resistant varieties has increased the need for and potential shift to cost-effective seed-applied nematicides as a possible control option.

•     (See Seed Treatment White Paper on this website for more information about all soybean seed treatment products).

Role of Emerging Crop Protection Technologies in IPM

•     Pest surveillance–for invasive and HR weeds, fungicide-resistant diseases, an invasive or resistant insect species–is an increasingly integral component of IPM.

•     Drones or unmanned aerial vehicles (UAV) offer potential for site-specific pest monitoring and pesticide applications. UAV’s can monitor large areas in a short time, and pests can be mapped before remedial applications.

•     Technologies that will allow UAV’s to distinguish and quantify specific pest infestations need to be developed and/or refined.

•     The ipmPIPE web-based database that is used to monitor and release real-time soybean rust observations is a valuable tool that can be expanded to include more diseases that affect major crops.

•     Improvement of automated pest management data analyses will allow the handling of large data sets. This will allow data from remote sensing to be used for site-specific management of pest problems such as weeds that have a “patchy” distribution so that blanket pesticide applications are not made. Another benefit from this improvement could be the identification of HR weed patches so that their seed production and/or shed is mitigated, thus extending herbicide effectiveness in a field.

•     Use of “smart” sprayers with a detection system in addition to a chemical spraying system will allow variable-rate spraying that will negate blanket pesticide applications in a field. These systems need to be enhanced in order to reliably distinguish weeds from the crop.

•     Use threshold- vs. prophylactic-based pesticide applications to: 1) reduce expenses; 2) reduce environmental impact; 3) prevent or delay pesticide resistance development and prolong efficacy of present MOA’s; and 4) preserve competitors and natural enemies.

•     Establish a pest-resistant crop by: 1) planting resistant varieties in those fields with known specific pest problems; 2) using cultural practices that limit pest survival and reproduction; 3) scouting and sampling to determine specific pest presence; and 4) not planting other crops or tolerating weeds that are alternative hosts to particular pests.

•     Thresholds that can be used for plant disease management are needed, but the complexity of disease development makes this an almost impossible task. In other words, all fungicide applications should be made according to disease pressure in the crop, which will likely be based on personal experience and the advice of knowledgeable Extension specialists and/or trained crop advisors.

•     Development of thresholds for weed management must take a long-term approach, but even this may not provide useable results because of crop or variety characteristics, weed densities, time of weed emergence, environmental conditions at a specific time in relation to crop development, weed seed production and the long-term persistence of these seeds, and the availability of an efficacious herbicide to control a present weed problem. Also, the absolute necessity to control weed seed production in order to mitigate HR weeds is paramount.

•     Control/reduce weed seed production to reduce the soil weed seed bank (See the White Paper on this website).

•     Develop cover crop systems that can be used in crop- and weed-specific situations to control/minimize the effect of HR weeds; determine if these systems host or otherwise impact other pest species.

•     The continued evolution of pests that become resistant to current management strategies and products increases the pressure on breeders and geneticists to continue/increase breeding efforts that will result in varieties that are resistant to pathogen and insect pests.

Preserving Crop Protection Chemistries and Traits

Broad adoption/use of new pesticide chemistries and genetic resistance traits, combined with lack of rotation of these chemistries and crop varieties and the off-label use of pesticides, have contributed to and continue to contribute to developing resistance in weed, fungal, and insect populations.

Decision making in pest management will increase in complexity because of the need to not only select pesticides that control the target pest, but also select those that will prolong the efficacy of present MOA’s and enhance the economic viability of the farming enterprise in a changing commodity price environment.

The Fungicide Resistance Action Committee, the Insecticide Resistance Action Committee, and the Herbicide Resistance Action Committee websites are excellent resources on this subject.
 

The future contribution of crop protection strategies and materials to crop productivity will depend on knowledgeable growers working in cooperation with adequately trained and knowledgeable crop advisors, retail field persons, and Extension specialists. Development and use of commercially available computer software programs and apps, along with other online decision-making tools, will increase in importance as crop pests evolve.

Collective adoption by producers of the best resistance and pest management practices must be done on an area-wide basis. All parties in the agricultural sector should provide/take advantage of IPM learning opportunities so that all producers are using the latest science-determined BMP’s for pest management in their specific operations.

Click here for links to articles on this website that provide in-depth information about many of the subject/issues highlighted above.

Composed by Larry G. Heatherly, April 2017, larryheatherly@bellsouth.net