We had some good winter wheat stands during 2024. We also had conditions that favored wheat diseases in many regions of the state. Here are a few considerations as we prepare for wheat planting this fall:
- Remove volunteer wheat and grassy weeds >14 days before planting wheat.
- Select wheat varieties with resistance.
- Consider seed treatments.
1. Remove volunteer wheat and grassy weeds >14 days before planting wheat.
Viruses were routinely detected in Missouri wheat samples submitted to the MU Plant Diagnostic Clinic in the spring of 2024 (Table 1). This included detection of the high plains virus, which was confirmed for the first time in Missouri (east central region).
Table 1 Viruses confirmed in Missouri wheat during 2024 by the MU Plant Diagnostic Clinic.
| Virus | % of Positive Samples* | Transmitter |
| Soilborne Wheat Mosaic | 5% | Fungus-like parasite that lives in soil |
| Barley Yellow Dwarf/ | 9% | Aphids |
| Cereal Yellow Dwarf | 7% | |
| Wheat Streak Mosaic/ | 58% | Wheat curl mite |
| High Plains/ | 2% | |
| Triticum Mosaic | 0% | |
| Wheat Spindle Streak Mosaic | 0%** | Fungus-like parasite that lives in soil |
*43 samples from across Missouri were submitted to the clinic for testing.
**Wheat Spindle Streak Mosaic Virus was not detected in 2024 samples but was detected in 2023 samples.
Management of viruses starts before planting. Why? Viruses require a vector or “transporter” to infect wheat. Insects and fungi are examples of vectors. Remove or reduce volunteer wheat and other-grass like plants so these vector populations cannot continue growing.
Figure 1 Wheat that tested positive for Wheat Streak Mosaic Virus at Columbia, MO in 2024.
Wheat virus symptoms generally include stunting and yellowish streaks on the leaves (Figure 1) and in severe instances yield losses can occur. Often lab testing is required to differentiate among these viruses, which can be important to determine appropriate management strategies. The wheat curl mite is an example of a vector. It is known to transmit wheat streak mosaic virus, high plains virus, and Triticum mosaic virus into wheat. The wheat curl mite has a lifespan of 14 days. Removing volunteer wheat and grassy weeds >14 days before planting wheat will help reduce wheat curl mite populations. Another example of a vector is the aphid, which transmit barley yellow dwarf and cereal dwarf viruses. Insecticide seed treatments may reduce the aphid population in years with high fall infestations. Select wheat varieties with resistance to these viruses when possible. Not all wheat varieties have resistance rating data available. However, when available, utilize this information in your seed selection process.
2. Select wheat varieties with tolerance to fungal pathogens
Fungal diseases were more prevalent in 2024 compared to the last couple of years. We observed stem rust, leaf rust, and stripe rust as well as Fusarium head blight and Stagonospora Leaf and Glume blotch (Figures 2 and 3).
Figure 2 Multiple fungal diseases were present on wheat during 2024.
Figure 3 Bleaching of wheat spikelets on the head are a symptom of Fusarium Head Blight.
We can employee integrated management practices to manage these diseases. Many wheat varieties have resistance ratings to fungal diseases. The combination of resistant wheat with timely fungicide applications has been quite effective in reducing some of our most problematic diseases such as Fusarium Head Blight (FHB)(Figure 4).
Figure 4 Fusarium head blight (FHB) disease index across different wheat varieties. S = susceptible to FHB; MS = moderately susceptible; MR = moderately resistant. Fungicide applications were made at 10.5.1 (anthesis). Graph summarizes 8 trials and was developed by K. Onofre as part of the United States Wheat and Barley Scab Initiative.
3. Consider seed treatments
Conditions during the June wheat harvest were wet and favored Fusarium head blight and glume blotch, and the pathogens that cause these diseases can infect the seed. Fungicide seed treatments can reduce seedling blight caused by diseased-wheat seed. In the spring we can come back with timely fungicide applications, if necessary, which will depend on weather conditions and disease observations.
To learn more about Fusarium Head Blight: https://cropprotectionnetwork.org/publications/an-overview-of-fusarium-head-blight
To learn more about Stagnospora Leaf and Glume Blotch: https://cropprotectionnetwork.org/encyclopedia/stagonospora-leaf-and-glume-blotch-of-wheat
To learn more about leaf rust of wheat: https://cropprotectionnetwork.org/encyclopedia/leaf-rust-of-wheat
To learn more about stripe rust of wheat: https://cropprotectionnetwork.org/publications/an-overview-of-stripe-rust-of-wheat