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Crop scouting school —

By Staff | Mar 13, 2009

Bob Hartzler, left, ISU Extension weed specialist, helps a group of students identify weeds during the 2009 Crop Scout School held last weekend at Iowa State University in Ames.

AMES – Agronomy professionals and producers from Iowa and surrounding states gathered at Iowa State University in Ames Saturday for an all-day event designed to inform and help them brush up on their crop scouting skills.

A quick overview was given to the 140 attendees during their first session, “Introduction to Crop Scouting.”

Virgil Schmitt, ISU Extension field agronomist from southeast Iowa, provided the group with the basic goals and personal characteristics each crop scout should possess.

The ultimate goal of a crop scout, Schmitt said is, “to improve producers’ profits by being a part of the crop production and protection team.”

In order to achieve this goal, he said in-season rescues or protective decisions; replanting decisions as well as recommended changes for succeeding seasons may have to me made.

Lori Abendroth, ISU Extension corn specialist, helps Will Axmear, a Nevada producer, with staging a corn plant at the 2009 Crop Scout School held last weekend at Iowa State University in Ames.

Schmitt also said a good scout must have a good work ethic, be willing to work long hours when necessary, be able to read maps, be very observant, be eager to learn and be an effective communicator and feel comfortable approaching the producer.

In addition they must also have a general understanding of agriculture, have common sense and also a respect for the client’s property.

Schmitt further explained to the class in detail of how to be an effective scout by making sure they have all of the necessary tools which range from a proper scouting kit to phone numbers of the producer and producer’s spouse and plat books and maps of the fields.

Will Axmear, a producer from Nevada, attended the crop scout school in order to gain more knowledge of what to be looking for in his own fields.

“I plan on doing more of my own scouting now and thought it’d be a good idea to take the class and learn more about what’s going on,” said Axmear.

“There’s been a lot of information at every session and the resources we have been given are nice.”

A minimum scouting kit, Schmitt said, should include a sweep net, trowel and spade for digging, tape measure, stakes, vials and bags for storing samples, a soil probe as well as a camera.

Knowing the economic thresholds, he said, is essential when notifying a producer of what is in their field, to help him decide what, if any, action should be taken.

Economic thresholds, Schmitt said, are most common for insects and there are a few developed for diseases with more being developed and there are also a few guidelines for weeds.

He stressed that it is critical for crop scouts to be safety conscience by knowing where are the restricted entry levels of any field and to be mindful of heat and sun effects. He also urged scouts to be careful of foreign items in a field that could’ve possibly been a part of a meth lab.

Schmitt informed the class that before working a field, have a predetermined pattern and to vary that pattern each time. Limit the size to 50 acres at a time and to avoid the outside 100 feet of a field.

Finding random areas to scout is also a good idea and he advised to look at the plant above and below the ground, besides just checking for pests, also check for population, and get an accurate estimate of the overall health of the plant.

The most important thing, Schmitt said, is what a normal plant looks like.

In order to help attendees get a better grasp on how a healthy plant is to look, Palle Pedersen, ISU Extension soybean specialist, provided a session on soybean growth and development, while Lori Abendroth, ISU Extension corn specialist, and Wade Kent, graduate research assistant, led the session on corn growth and development.

Growth staging of a soybean plant, Pedersen said, said is critical and shows the speed of growth of the plant during the season.

He then instructed the class on the different stages of the soybean growth and development by explaining what the different stages are and how to count them.

The class worked on calculating growing degree days then Abendroth, using actual corn plants and slides, explained to them different corn staging methods.

She said there are three common corn staging methods which include, horizontal leaf method, which is most commonly used by hail adjusters; the herbicide label method that includes the height of the plant, and the leaf collar method, which Abendroth recommends using when scouting corn.

The leaf collar method, she said, was developed by ISU in the 1960s and helps determining the growth stage of the plant by counting each leaf blade that has broken away from the stalk.

Kent provided a detailed presentation on seed development and emergence beginning with seedling anatomy and the three factors to consider for a uniform germination and emergence.

Those three factors, according to Kent, include soil moisture in the seed zone, where kernels must absorb 30 percent of their weight in water; proper soil temperature of 50 degrees or above and good seed-to-soil contact.

If there is a problem with a seedling emerging, Wade said, it will help to recognize the problem by looking at compaction, insects and weather.

Spotting weeds

Weed identification was provided by Bob Hartzler, ISU Extension weed specialist.

After explaining the definition of a weed and traits that contribute to weediness, Hartzler explained classification of weeds: botanical, family and life cycles to help a scout or produce decide what pest they are dealing with.

Tools crucial for identifying a weed include books and pamphlets, a computer, hand lens and, most importantly, other people, such as agronomists or Extension specialists.

Hartzler described keys that are useful for people who have little experience in identifying weeds and offered different examples on how to determine differences among weeds.

Damaged plants

Schmitt led a session that dealt with crop injury and provided the classes with a preview leading up to the crop diseases and insects portion of the school.

Schmitt presented the students with many slides showing several symptoms and let them attempt to diagnose problems.

“There are a lot of look-a-like symptoms in soybeans,” Schmitt said, adding that what one thinks may be wrong, may not be accurate.

In order to diagnose a problem properly, Schmitt advised to check the foliar part of the plant, the roots and the surrounding area to decide if the problem is herbicide, disease, insect or a nutrient deficiency.

Schmitt said his number one rule in crop scouting is to “Never leave a soybean field without digging up the plant and looking at it,” as soybean cyst nematode is frequently overlooked.

For scouting corn, he gave some troubleshooting tips in helping to decide if the issue is a nutrient deficiency and if that means the nutrient is lacking in the soil, or the nutrients are there, but the roots can’t move it, insects, herbicides or any other possible man-made problems.

Spotting diseases

Alison Robertson, assistant plant pathology professor at ISU and Daren Mueller, ISU Extension program specialist, conducted the plant disease identification course.

Robertson informed the group on how to scout for a field for disease and explained that if there is a disease out there effecting the crop’s health there must be at least three different things going on to cause it.

When scouting for a disease, Robertson said to look at the big picture, or look at the field at field level. See if the problem is scattered randomly or in a pattern. Is the area by a fence or by slopes?

Disease scouting methods include random, arbitrary, systematic and stratified. It is important to have a pattern to follow throughout the field when using these methods, she said.

“Scouting depends on the disease and you may need to change scouting patterns for certain kinds of diseases,” said Robertson.

When assessing a disease, Robertson said to note the specific time (growth stage, date and days after an application). If it is a foliar disease, to assess a specific leaf position or specific area of canopy and do a complete plant assessment.

When collecting and recording information, she said it is very important to know the exact hybrid or variety, know the weather and consider the time of year.

“Diseases show up at different times of the year, yet often predictable times during the season,” she said.

It is also imperative to collect background information for the entire field, such as previous crops, chemicals applied, soils, planting dates, etc.

She then offered a quick run through of common corn disease such as leaf blight, gray leaf spot and common rust.

Mueller provided the group with information pertaining to soybean diseases and the most common ones found.

Symptoms of soybean cyst nematodes will depend on the cultivar and the environment and the plants will usually be stunted and yellow.

Bacterial pustule is a soybean disease that can be confused for rust, and is frequently called phytophthora damping off, white mold, sudden death syndrome and brown stem rot.

“If you are unsure of what the disease is, send it into the ISU Plant and Insect Diagnostic Clinic,” said Mueller.

Spotting insects

Jesse was on hand for the school to present to the students insect identification.

“Knowing the growth and development of an insect matters because we may see the adult but it could be the young larvae doing the damage,” said Jesse.

Corn insect pests to be watching for when scouting fields, Jesse said include the Seedcorn maggot, wireworms, white grubs, black cutworm, stalk borer, European corn borer, armyworm, western bean cutworm and corn rootworm beetle.

For soybeans, she said scouts should be on the look out for bean leaf beetles, soybean aphid and spider mites.

For scouting insects, Jesse recommends carrying Ziploc bags, vials, hand sanitizer, a beat sheet (a white towel or paper for “beating” the plant onto for an easier examination of the pests away from the plant), sweep net and a digital camera.

Contact Kriss Nelson at jknelson@frontiernet.net.

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