Moses Lake, WA 98837, USA

Determining problems in alfalfa fields

By RACHAL PINKERTON
Staff Writer

MOSES LAKE — Anyone who has ever had a garden or flower bed has had to deal with sick or dying plants. Figuring out why those plants aren’t healthy isn’t always easy. Farmers can have the same problems, only on a much larger and more costly scale.

At the 2019 Hay Conference in Moses Lake, Steve Norberg, a Washington State University Extension agent, explained a process, first developed by James Green from Oregon State University in 2003, that can help hay farmers identify problems with their alfalfa.

The first step in determining why plants are sick or dying is to simply describe and define the problem. Some questions to ask at this stage include the following:

- Do the plants look normal for the time of year?

- Does this problem affect both the roots and the foliage?

- Is the plant dead, is there a pattern to the problems?

- Does the problem only affect certain area of the plant?

- What is the difference between the good and bad areas of the plant?

- What is the difference between the various areas in the field?

- Are the plants stunted? If so, how much?

- If it looks like a pest problem, what evidence did they leave behind?

Once these questions have been answered, it is time to observe the patterns caused by the damage. At this stage, it is helpful to step back and look at the whole field. Norberg recommends finding an elevated vantage point to look at the field. The patterns present in the field are usually a good indication of whether the problem was caused by biotic or living organisms, such as insects or disease, or is the result of abiotic, non-living, field practices, such as spraying, fertilizing or harvesting. Biotic problems tend to be circular or irregular in shape. Abiotic issues tend to be in straight lines or have uniform patterns.

Looking at weeds can also indicate what may be affecting the field. If the weeds are affected, the problem is probably abiotic. If the field has strips in is, it is helpful to see if it matches the footprint of equipment that has been used in the field.

The location of damage to leaves can be a sign of herbicide. Plants that have abnormal leaves on the bottom, but have normal leaves on the top could have been affected by herbicide applications previously applied to the field.

The next step in the process is to review the records of the field. Reviewing what other crops have previously been in the field and what issues the field has in the past may answer some questions. It is also important to know whether the soil is good or bad.

A review of all chemicals put on the field should be made. Determining when chemicals were applied may shed some light. It is also important to look at the pest resistance ratings for the variety of alfalfa that is planted in the field.

How much a field is watered may affect alfalfa plants. The amount of water used and the quality of the water should be analyzed.

One problem that can cause alfalfa to grow poorly is a seed bed that is not firm enough. If plants are healthier in the wheel tracks, that may be a good indication of what the seed bed was like.

Planting too late in the season may cause huge problems for an alfalfa field. Those fields that are planted during normal planting seasons may be affected by weather.

Reviewing all the records of the field is helpful in determining problems in a field.

Once the records have been reviewed, consider when the symptoms first appeared in the field. Depending on the problem, they may have increased or decreased.

If all the above questions have been answered and the problem still remains a mystery, it is time to get in touch with local extension agents or do some research online and in books. Norberg recommended the website pnwhandbooks.org.

Laboratories can confirm the presence of disease or nematodes, microscopic worms that feed on fungi, bacteria and other nematodes. Norberg suggested that samples sent into laboratories should not be sent close to the weekend to allow them to be fresh. Before sending anything into a laboratory, check their website for instructions on how to send samples and verify if a fee is required.

It is helpful to consider other problems that may be in the field. Do the plants have a mineral deficiency and are they being over watered are two questions that should be considered.

Once all the questions have been asked, test the conclusions. This may be an increase or decrease in water, a water test or applying chemicals to a section of the field.

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