New transgenic crops are currently being developed which will be tolerant to dicamba and 2,4-D herbicides. This technology could greatly benefit producers who are impacted by weed species that have developed resistance to other herbicides, like glyphosate-resistant Palmer Amaranth. Adoption of this new technology is likely to be rapid and widespread which will lead to an increase in the amount of dicamba and 2,4-D applied each season. It is well-documented that these herbicides are very injurious to soybeans, cotton, tomatoes, and most other broadleaf crops, and their increased use brings along increased chances of physical spray drift onto susceptible crops. Because of these risks, research is being conducted on new herbicide formulation/spray nozzle combinations to determine management options which may minimize physical spray drift.

Dicamba drift is a common issue and has been known to cause injury and yield reduction in a wide range of susceptible crops. A study was established to evaluate the effects of a simulated drift on the plant growth and yield of two pumpkin varieties (Cucurbita pepo ‘Magic Wand’ and C. moschata ‘Autumn Buckskin’) during 2019 and 2020 at the Southern Illinois University Horticulture Research Center in Carbondale. Six rates of dicamba were applied to simulate a mid-post-emergence application made in soybean which drifted onto pumpkins at two growth stages, 8-leaf and 12-leaf. These two pumpkin growth stages would be the approximate size of pumpkins when a mid-post-emergence application would typically be made in soybean. The 12-leaf growth stage also corresponds with Simulated drift rates were targeted at 1/1026, 1/513, 1/256, 1/128, 1/64, 1/32 of a 0.56 kg ae ha-1 rate, corresponding to 0.00056, 0.00112, 0.00224, 0.00448, 0.00896, and 0.01792 kg ae ha-1. Actual dicamba deposition was measured used filter papers (surface area = 176.1 cm2) in each treatment and these measured exposure amounts were used in correlational analyses with pumpkin injury, growth, and yield responses. Pumpkin plants did not develop chlorosis or necrosis at any point of the growing season with any of the dicamba application treatments. However, some injury and stunting were observed on pumpkin plants, regardless of drift rate, although pumpkin plant growth and responses were minimal at the drift rates evaluated. Our results indicated that typical dicamba drift rates cause minimal dicamba injury on pumpkin plants at 8- and 12-leaf growth stages with negligible effects on resulting yields. Pumpkin plant injury and stunting would most likely be observed at dicamba drift rates > 1 μg per 176.1 cm2 of leaf area, which converts to 0.62 g per ha. Pumpkins receiving dicamba drift at different growth stages appear to be less sensitive than some other crops, but a drift event at higher rates than those evaluated in this study may impact plant growth and yield. It is important to note that other pumpkin varieties or other Cucurbita species not evaluated in this study may be more susceptible. Producers using dicamba in soybean rotations that are near pumpkin fields should spray under proper wind, temperature, and humidity conditions to best mitigate the occurrence of any drift events. Nomenclature: 3,6-dichloro-2-methloxybenzoic acid, Cucurbita pepo, C. moschata, dicamba, pumpkin.

Agricultural production has observed many changes in technology over the last 20 years. Producers are able to utilize technologies such as site-specific applicators and remotely sensed data to assist with decision making for best management practices which can improve crop production and provide protection to the environment. It is known that plant stress can interfere with photosynthetic reactions within the plant and/or the physical structure of the plant. Common types of stress associated with agricultural crops include herbicide induced stress, nutrient stress, and drought stress from lack of water. Herbicide induced crop stress is not a new problem. However, with increased acreage being planting in varieties/hybrids that contain herbicide resistant traits, herbicide injury to non-target crops will continue to be problematic for producers. With rapid adoption of herbicide-tolerant cropping systems, it is likely that herbicide induced stress will continue to be a major concern. To date, commercially available herbicide-tolerant varieties/hybrids contain traits which allow herbicides like glyphosate and glufosinate-ammonium to be applied as a broadcast application during the growing season. Both glyphosate and glufosinate-ammonium are broad spectrum herbicides which have activity on a large number of plant species, including major crops like non-transgenic soybean, corn, and cotton. Therefore, it is possible for crop stress from herbicide applications to occur in neighboring fields that contain susceptible crop varieties/hybrids. Nutrient and moisture stress as well as stress caused by herbicide applications can interact to influence yields in agricultural fields. If remotely sensed data can be used to accurately identify specific levels of crop stress, it is possible that producers can use this information to better assist them in crop management to maximize yields and protect their investments. This research was conducted to evaluate classification of specific crop stresses utilizing hyperspectral remote sensing.

Tomato is a major horticulture crop grown across the globe. Unfortunately, its yield is reduced by 25% because of auxin herbicides and glyphosate drift. In this present study, wild germplasm of tomato was screened for herbicide tolerance. From the greenhouse study nine accessions for glyphosate and 2,4-D, eleven accessions for dicamba, five accessions for quinclorac, eight accessions for aminocyclopyrachlor, and two accessions for picloram and aminopyralid were identified to be tolerant. A few accessions were selected from each herbicide tolerant group for field trials at two locations in Mississippi in 2016 and 2017. Results indicated that TOM18 was most tolerant to dicamba herbicide, while TOM87 and TOM129 to glyphosate and quinclorac herbicide, respectively, on the basis of yield and injury. Molecular experiments were conducted to measure the genetic diversity among diverse germplasm. Genetic diversity analysis showed wild accessions to be highly diverse as compared to cultivated tomato.

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