Sample Diagnosis

From January to June 2024, the MU Plant Diagnostic Clinic has received 297 physical samples and 139 digital samples (Figure 1). Among all the samples, plant disease diagnosis accounted for 283 out of 436 samples, while 8 samples are for insect identification services and 6 samples for weed identification (Figure 1). The month of June was the busiest month so far in 2024, with 142 samples throughout (Figure 2). The number of digital samples received so far is similar to 2023.

Figure 1 Number of samples by service type.

Figure 2 Comparison of physical sample number by month in 2021-2024.

Figure 3 Comparison of digital sample number by month in 2022-2024.

Field Crops are the largest sample category with 110 samples, followed by fruits (98), ornamentals (56) and vegetables (16) (Figure 4). Wheat (46), Soybean (31) and corn (19) compose the three major crop categories (Figure 5).

Figure 4 Distribution of samples submitted for disease diagnosis by sample type.

Figure 5 Type of field crops submitted for disease diagnosis.

Figure 6 Diseases and abiotic issues diagnosed among the submitted samples.

Thanks to the free wheat virus tests offered by the clinic, we have received 46 wheat samples which is a big leap of sample number comparing to 32 samples in 2023, and 10 samples received in 2022. We have tested for several wheat viruses positive in Missouri this year, including Wheat streak mosaic virus (WSMV), Wheat spindle streak mosaic virus (WSSMV), Soil-borne wheat mosaic virus (SBWMV), Barley yellow dwarf virus (BYDV), High Plains virus (HPV), and Cereal yellow dwarf virus (CYDV). The geographical information, disease and plant variety data had been collected to monitor the distribution of these viral diseases and plant resistance among different varieties so that they can be used to develop research program for identifying resistant lines that help controlling wheat health problems. With collaboration with Mizzou Field Crop Pathology group, our clinic remains committed to identifying and managing these viruses to help farmers protect their wheat crops in the future.

Relatively wet conditions in the spring and early summer have posed challenges for early-season soybean growth and development. Several soybean samples submitted to the clinic were infected by multiple soil-borne pathogens. Phytophthora crown and root rot is the main threat in the early development stage, in addition to Pythium root rot caused by Pythium spp., Fusarium crown and root rot caused by Fusarium spp., and Rhizoctonia root and stem rot by Rhizoctonia solani. No Charcoal rot disease was observed. As the summer progresses, and the climate becomes drier, it is expected the oomycete pathogens will affect crops less later in the season but we are closely looking out for the emergence of several severe fungal root rot and stem rot diseases, such as Sudden Death Syndrome, Red Crown Rot and Brown Stem Rot. Other soybean diseases are either from environmental stress or chemical damage, as several soybean samples were evaluated and suspected to have herbicide injury with the help of MU Extension Weed scientists.

In addition to soybean diseases, diagnosed corn diseases include gray leaf spot, tar spot, common and southern corn rust and nutrient deficiency. Based on the wheat virus diagnosis results, more than 85% tested wheat samples carry WSMV, and we didn't see as many SBWMV, WSSMV and BYDV positive samples as last year. HPV was detected from a sample collected in Montgomery County and this is the first time that this viral disease is reported, and it can cause disease in both wheat and corn.

For appropriate diagnosis, the MU Plant Diagnostic Clinic can help you confirm if your plant has this disease. We encourage you to visit our website and review submission guidelines before submitting your sample. If possible, you may take photos and send them to plantclinic@missouri.edu.

We have a 7-minute video about sample submission guidelines on YouTube to help you submit your sample step by step.

Contact Information:

University of Missouri-Plant Diagnostic Clinic
28 Mumford Hall
Columbia, MO 65211
Phone: 573-882-3019
Email: plantclinic@missouri.edu
Twitter: https://twitter.com/MUplantclinic