With many area fields are still not planted and many farmers still working to get those fields planted or struggling with re-plant issues it's hard to focus on the crops that are up and growing. It's always a hard sell to get fields scouted regularly, but given the extraordinary weather we've had this planting season, it is necessary to be particularly diligent about managing and protecting the crop that is present. Fungal diseases in the soybean and corn crops are in the perfect environment to cause losses. For above ground fungal leaf disease scouting, make observations on ten plants in ten places in the field following a typical zig zag scouting path.

Fungal leaf blights that start developing in the corn at the premature growth stages we have this year could be a serious yield loss issue. Leaf blights find warm wet weather in fields that are in continuous corn or have an abundance of corn residue to be a perfect spot to setup house. Anthracnose leaf blight has already been found in west central Illinois. Anthracnose forms large lesion dramatic lesions on the lower leaves. The lesions are usually fairly large ragged and dark purple. While normally seedling anthracnose isn't a big problem for us this time of the year, the crop is not usually so immature and so it does bear watching particularly if we continue to get regular rains and the disease begins moving up the plant from the lower leaves. Anthracnose can also show up in the corn later in the season as a top dieback or a stalk rot, but it's the foliar symptoms that need to be scouted for currently.

In the soybeans it's not hard to find small brown lesions on the lower leaves now. Brown spot is caused by the fungus Septoria glycines. Symptoms usually appear first on the unifoliate leaves very early in the season as brown spots that are somewhat angular to irregular in shape. Early season infection is often mis-diagnosed as normal leaf senescence. The spots will develop both on the top and bottom surface of the leaf. Some leaves that become heavily infected will turn yellow and drop off the plant. Under periods of warm wet or humid weather the disease will progress up the plant. Favorable weather conditions have led to the disease development that we are seeing now.

Yield loss can occur if the plant is severely defoliated from the disease. Leaves that are infected later in the season often have a rusty brown appearance from numerous lesions. Leaf tissue around the lesions is usually yellow as well. The brown lesions can develop on the stems and petioles as well, it is hard to make a diagnosis from these stem lesions though because of their similarity to other diseases. Significant yield loss is very rare for this disease, fungicide treatment is almost never recommended nor of economic value if the disease stops developing as we enter into early to mid July. Resistant varieties are not available.

The crop that is surviving and beginning to thrive this season has a higher value than in many prior seasons. Scouting will be essential for you to make sound economic and environment decisions for pest management