Research and Updates

Robotic Weeder

Suppress 

During a control efficacy trial conducted at the CREC Suppress EC was demonstrated to control up to 85% of weed grass growth in the field, specifically barnyardgrass. During this trial, an 18% v/v mixture of Suppress with a water carrier of pH 2.8 was used to yield these results. It is important to ensure that the water carrier is of a pH < 3; pH of water carrier can be lowered using products high in citric acid such as lemon juice.

When tested in greenhouse trials, results indicated that Suppress EC works best on plants 7cm in height or less. Results also demonstrated close to 100% control of palmer amaranth 5cm in height and approximately 90% control of palmer amaranth 7cm in height. Suppress EC also performed about 30% better than Scythe at controlling 10cm palmer amaranth.

 

Cryogenic Weed Control

Cryogenic weed control is accomplished by freezing the exposed tissues of weeds before destroying them with mechanical pressure. Freezing of plant tissue is done by spraying plants with liquid nitrogen and destruction of plant tissue is carried out by using a ballasted roller. The mechanical pressure of the roller not only fractures the exposed frozen plant tissue but also disrupts organelles in young leaves and meristematic tissue below the ground.

Based on trials carried out to test control of morning glory, the best results were obtained when using a brass nozzle affixed 30cm above the ground applying a high output of liquid nitrogen (9360l/a) at a high pressure (41kPa).

Cryogenic weed control is a potentially more sustainable management method in the long run compared to using herbicides. This is because liquid nitrogen leaves no chemical residues and does not affix nitrogen to the soil. In addition, this method is fueled by a readily available resource in atmospheric nitrogen.

 

Anaerobic Soil Disinfestation (ASD)

A greenhouse experiment led by graduate student Gursewak Singh is being carried out to test the efficacy of anaerobic soil disinfestation as a method of weed suppression. Each experimental unit consists of a 5-gallon all-purpose bucket filled with surface soil from a USDA organic field and treatments consisting of a combination of Molasses (carbon source) with four allelopathic-organic herbicides amendment (sweet potatoes, liquid corn gluten, chicken manure, and mustard meal). These were chosen as relatively widely available agricultural by‐products that could be used as organic amendments for ASD treatment which also vary in relative microbial availability. Buckets containing only untreated soil were also prepared as controls. Economically significant weeds present in tomato production were seeded in each bucket. Mesh bags containing soil inoculated with the pathogenic bacterium Ralstonia solanacearum were buried in each bucket. Oxidation-reduction electrodes were installed in each bucket to evaluate soil anaerobicity continuously via an automatic data logging system. Inoculum bags were sampled at the end of the six-week ASD period. In addition, the percent weed emergence and weed biomass data was recorded.

We will repeat the whole experiment in the summer of 2020.

ASD Trial

Figure 1: ASD trial buckets

ASD Control vs Treated

Figure 2: Weed suppression in ASD molasses + chicken manure treatment vs untreated control

 

Robotic Weed Control

The robotic weeding trials to be carried out will be done using the Husky unmanned ground vehicle. This UGV will be equipped with cotton harvesting equipment in addition to a sprayer for herbicide application. It will be outfitted with a mechanical actuator for accurate herbicide spraying as well as equipment to be used for cotton harvesting. 

 

Cover Crops

Cereal ryegrass has been shown to reduce wild mustard proliferation by about 70% 

Regal Graze Ladino Clover 12-15 lbs /ac reduces sedge by 70% and corn spurry by 80%

Red Clover reduces corn spurry spread by 75% and wild mustard growth by 80%

Rye grass

Figure 1: Ryegrass Cover

Ryegrass being used to control wild mustard proliferation.

Ledino clover

Figure 2: Ledino Clover Cover

Ledino clover being used to control corn spurry proliferation.

Red clover

Figure 3: Red Clover Cover

Red clover mulch being used to control corn spurry and wild mustard proliferation.

Crimped rye grass

Figure 4: Crimped Ryegrass

Sweet potatoes planted into crimped ryegrass cover crop.

Crimped ryegrass photo credits: Dave Robb and Geoff Zehnder