FORESIGHT FOR SUCCESSFUL CROPPING SYSTEMS

Things to Monitor in the 2003 Crop

By Zachary Fore
U of M Cropping Systems Specialist
forex002@umn.edu

If we are fortunate, by the time you read this article it is early May and planting is well underway. Once planting is completed you can turn your attention to other issues.  Each year is different, and predicting what problems are likely to occur is uncertain business. I don’t claim to know what challenges 2003 will bring, but this article identifies some things to pay attention to, particularly in wheat and soybeans.

Crop Stand
Getting a good crop stand is critical for obtaining maximum yields of any crop.  Many factors contribute to getting a good crop stand, including seed quality, planting rate, soil conditions, planting depth, and planting method.  For wheat we are generally shooting for 1.25 million plants per acre, and for soybeans 150,000 to 200,000 plants per acre. After emergence, it is a good idea to check to see how close you came to achieving your desired stand, which really doesn’t have to take a lot of time. 

For stand counts in narrow row spacing, a hoop works very well.  If you cut a 7’5” length of anhydrous tubing, garden hose, or similar substance and connect the ends you will have a hoop with an area of 1/10,000th of an acre.  Toss it in the field randomly in several locations and count the plants inside the hoop. Multiply the number by 10,000 and you have an estimate of your population per acre.

For example, if you count 96 wheat plants inside the hoop, that calculates out to a plant population of 960,000 plants per acre.  For wider row spacings it is better to count a specific number of feet of row. The length of row required to obtain 1/1000th acre is 17’5” for 30” rows, 23’9” for 22” rows, and 34’10” for 15” rows.

Wheat Leaf Diseases
Leaf diseases are a serious potential problem in wheat every year. However, many factors affect the degree and severity of leaf diseases. Whether or not you need to apply a fungicide is an in-season decision determined by the variety you have planted, the condition and value of the crop, previous crop, the amount of disease present at a given time, and the weather. The only way to know whether you need to apply a fungicide or not is to scout fields and assess these factors.

Fusarium Head Blight (Scab)
Scab is also a serious potential threat each year, particularly in the Red River Valley.  As with leaf diseases, many factors affect the degree and severity of scab.  And, as with leaf diseases, fungicide treatment for scab is an in-season decision based on numerous factors. North Dakota State University has created a web site that can help you assess the important factors to consider when determining if a fungicide application is a good economic decision for leaf diseases or scab. You can visit the site at: www.ag.ndsu.nodak.edu/cropdisease .

Root Rot and Other Stand Reducing Seedling Diseases in Soybeans
In many areas, soybean is grown every other year in the crop rotation. Because of this short crop rotation, we need to be especially aware of increasing disease problems. Some growers have reported more problems with seedling mortality. Observing plants as they emerge and taking stand counts will help assess whether seedling diseases are becoming an increasing problem.

Sclerotinia (White Mold)
White mold is a disease that is a problem in many broadleaf crops including soybeans.  Short crop rotations can increase the potential problems with white mold.  White mold spores can survive many years in the soil, so knowing the potential for this threat is important for determining what crop to grow in the future.

Soybean Aphid
During the last two years we have seen the soybean aphid be a problem all the way up to the Canadian border. We don’t know if they will be a problem in 2003 or not, but we know the potential is there and we will have to watch for them.

Soybean Cyst Nematode (SCN)
We know that SCN is a significant problem from central Minnesota and south. As soybean acreage increases in northern Minnesota and North Dakota, we need to watch to monitor the spread of SCN. Once it is identified, precautions can be taken to limit its spread and manage it.  Look for yellow, stunted plants, particularly near field entrances. SCN typically spreads in the direction of tillage, creating an oval pattern. Plants can be dug up, washed, and physically inspected for SCN.

 The University of Minnesota Extension Service has soybean production information online at www.soybeans.umn.edu/

I have no doubt that 2003 will bring many challenges and some surprises. The potential problems detailed above are just a few, specific examples of things to keep an eye out for. Most problems can be managed if we identify and treat them in a timely manner.