Insignum AgTech has begun a collaboration with researchers in Purdue University’s College of Agriculture and College of Engineering to create tools for farmers to identify early stages of tar spot disease outbreaks in their corn plants.

The collaboration is supported by grants from the Indiana Corn Marketing Council and an Innovation Voucher from the state of Indiana.

Insignum CEO and Purdue alumnus Kyle Mohler said the work brings together expertise in three areas:

• Insignum uses DNA already present in corn plants to develop a new gene that reveals infections at an early stage. The gene uses the plant’s innate response to a fungal spore to cause leaves to form purple spots at the site of infection about a week before disease symptoms can be identified.
• C.D. Cruz, associate professor of botany and plant pathology, is one of the foremost experts in the U.S. in phenotyping tar spot in both greenhouse and field conditions. His work focuses on understanding the epidemiology of the disease. He and his team members Alex Acosta, Mariela Fernandez and Andrés Cruz of the Cruz Lab are inoculating Insignum corn with tar spot to test how the plants reveal the disease prior to the onset of symptoms.
• Jian Jin, associate professor of agricultural and biological engineering, has developed LeafSpec, a patented, hand-held, hyperspectral plant leaf scanner that studies physical characteristics of plants, including early disease symptoms, nutrient deficiency and response to chemical treatments. He and his team will capture images of corn plants in the greenhouse to determine if the color changes can be seen faster and more clearly with the device.

Jin’s team also will develop algorithms that pick up the color changes from drone imagery in Insignum’s 2024 field trials. The work may produce intellectual property to enhance scouting efforts when Insignum commercializes its plant genes.

Tar spot and its damaging effects 

Tar spot disease lessens a corn plant’s ability to absorb sunlight, thereby weakening the plant and reducing yield. The disease is caused by the Phyllachora maydis fungus. It creates raised, bumpy black spots called stromata on corn husks, leaves and stalks. Each individual stroma can produce thousands of fungal spores that can quickly infect other plants and fields.

Mohler said tar spot was first detected in the U.S. in 2015.

“By 2023 it was the most damaging pathogen to corn in the country,” he said. “Tar spot’s rate of spread, the amount of damage it causes and the fact many U.S. corn varieties aren’t resistant makes it the most concerning corn disease to American farmers.”

Mohler hypothesizes that Insignum’s technology will turn corn leaves purple to identify the presence of tar spot in a corn plant.

“Farmers can then treat their crops to prevent damage from this devastating disease,” he said. “Treating at the right time is critical to treat the disease. It is challenging to get correct.”

The collaboration is expected to last through the end of 2024.