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• Field Scouting
• Crop Management
• Disease Management
• Disease Images
• Insect Management
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• Weed Management
• Weed Images

Chapter 1

1. Introduction
2. Timing of Field Scouting Operations
• Scout Calendar
  Scout Calendar as text
3. Scouting Tools and Techniques
4. Number of Sampling Locations
• Table 1-1,Number of Recommended Sampling Locations based on Seed Corn Field Size and Pest
5. Scouting Pattern
6. Determining Plant Population and Pest Infestation
• Table 1-2,Length of Row Required for a Thousandth of an Acre at Various Row Widths
7. Recording Field Observations
8. Guidelines for Collecting and Submitting Plant, Insect or Soil Material for Diagnosis or Identification
• Field Scouting Report
• Field Record Form

Introduction

Crop scouting is the regular examination of fields to accurately identify yield-limiting factors during the growing season. Scouting provides an objective summary of the crop condition and pest situation in a field. Factors limiting the productivity of a field often arise suddenly and must be corrected quickly to preserve the full yield potential of the seed corn crop.

Every field season should begin with the recording of vital field information on soil fertility and crop inputs on a field record form. This information, combined with regular field scouting, accurate identification and diagnosis of problems and a record of those observations, makes for a successful crop monitoring program. Click on this link for an example of a field scout report. The information obtained from field scouting is useful in determining if any immediate actions should be taken. The information recorded is also useful for future reference to avoid problems in subsequent years.

Timing of Field Scouting Operations

Seed companies vary in their scouting programs but all understand that early recognition of pests and their control will minimize their economic impact on the seed corn crop. Insect and disease scouting calendars included in this manual will highlight the timing associated with the common seed corn insects and diseases found in Ontario and will assist both the producer and company scouts.  It is important to monitor fields consistently and frequently since pest dynamics can change rapidly throughout the season.   Seed corn inbreds vary in their susceptibility to diseases, herbicides, etc, therefore note any special inbred characteristics prior to visiting the field.  Plant populations and synchronicity between male and female inbreds are critical for achieving good yields, evaluate crop stands within 2-3 weeks after plant emergence. Early in the growing season, scout weekly. When approaching a control threshold, such as the application of a post­emergent herbicide, insecticide or a fungicide, fields may require scouting daily.

Precaution: Prior to entering any seed corn field, note whether the field has been sprayed and if the re-entry interval has passed. Later in the season, bi-weekly scouting is normally sufficient. Keep in mind that some insects and diseases occur later in the season and my approach control thresholds in a matter of days. Examples of such pests include European corn borer, armyworm, leaf diseases and stalk rots. If field and weather conditions favour these later-searson pests, scouting should continue weekly.

Scouting Tools and Techniques

Tools used to monitor crop development and pests vary with the crop and the pest.  Basic field scouting equipment includes:

• A clipboard with field scouting forms or a notebook
• Field maps
• A shovel, tape measure or meterstick
• A pocketknife, hand counter
• Plastic and paper bags for collecting specimens
• A 10X hand lens

Other tools could include aerial field images, a camera, labels for identification, reference guides, a sweep net, vials and isopropyl alcohol, sticky cards or traps to detect insect pests, a gps unit to mark the location, flagging material, etc. It is also wise to wear appropriate clothing for protection from the sun and from unknown risks such as poisonous plants and mosquitoes. Be aware of recent pesticide treatments applied to the field and obey re-entry intervals indicated on product labels.

When scouting for insects that move too quickly in the canopy to be spotted at a glance, it is sometimes easier to use the beat cloth or sweep net. A beat cloth can be spread on the ground between two rows of corn. The corn plant can then be pulled over the cloth and shaken vigorously so that any insects on the plant are dislodged onto the cloth. The insects can then be easily identified and counted.

Number of Sampling Locations

Scouting involves walking through a field and stopping at a number of locations to make observations. The number of sampling locations in a field depends on factors such as field size, crop, pest, etc. The general number of sampling locations for a range of seed corn field sizes is displayed in Table 1–1, Number of Recommended Sampling Locations Based on Field Size and Pest. For scouting purposes, fields larger than 16 ha (40 ac) should be split into units of 16 ha (40 ac) or less.

Scouting Pattern

There are a few factors to consider when determining what scouting pattern to follow in your field. Use a scouting pattern that includes changes in inbred variety, soil type, past cropping history, fertilizer/manure application and any other factors that can affect plant growth. The pattern should cover all parts of the field and should vary each time the field is scouted. See Figure 1-1,Scouting Patterns.

• Sampling locations should be selected on the basis of a predetermined random pattern, as opposed to factors such as crop appearance, etc.
• Start scouting at least 20 m (66 ft) into a field. Outside rows and headlands should be avoided in the scouting pattern unless there are specific reasons for sampling these areas.
• Start scouting at least 20 m (66 ft) into a field. Outside rows and headlands should be avoided in the scouting pattern unless there are specific reasons for sampling these areas.

Pests Uniformly Distributed Across the Field

When scouting for pests or problems that you expect to occur uniformly in the field or for pests and problems whose distribution pattern is unknown, distribute the sampling locations evenly across the field as shown above. This pattern is also appropriate for soil sampling.
See Figure 1-1, Scouting Patterns.

Pests that fit this scouting pattern include corn rootworm, european corn borer and stalk rots.

Pests Expected in Headlands or Outside Rows

When scouting for pests or problems that you expect to appear on headlands or in outside rows, distribute the sampling locations evenly around the edges of the field.
See Figure 1-1, Scouting Patterns.

Pests and problems that fit this scouting pattern include armyworm and soil compaction.

Pests Developing in Specific Areas of the Field

When scouting for pests or problems that you expect in particular parts of a field, concentrate sampling locations in areas where the problem or pests are most likely to be found.
See Figure 1-1, Scouting Patterns.

Pests that fit this scouting pattern include seedling diseases or root rots in damp clay soils and black cutworms in weedy patches.

Determining Plant Population and Pest Infestation

Plant population and some pest infestation levels in seed corn are determined by making counts in areas of a given size and then multiplying that number by a factor to obtain the population per acre. For seed corn and other row crops, plant population can be calculated by counting the number of plants in a thousandth of an acre and then multiplying the count by 1,000 to obtain the number of plants per acre. Table 1–2, Length of Row Required for a Thousandth of an Acre at Various Row Widths, lists the row length equal to a thousandth of an acre at various row widths.

Many insect action thresholds are expressed as the average number of insects per plant, per square metre or per foot of row.   Disease action thresholds are often expressed as number of damaged plants per foot of row, percentage of defoliation or damage. Regardless of the method used, at least 10 random counts should be taken in each field to determine average populations.

Recording Field Observations

Field scouting records are an essential tool to use for both current and future seed corn management decisions.  Most seed corn companies and scouts use a field scouting form which facilitates and standardizes the recording of field observations. Once recorded, the scouting data should be added to the field record files. Computer software is also available to record and manipulate data from field observations.   New technology such as personal data assistant (pda’s) have increased in popularity and have become very useful tools for in-field data collection.

Field Record Form
Field Scouting Report

Information To Be Recorded Should Include:

• Field location and scouting date
• Growth stage and condition of male and female inbreds crop
• Inbreds
• Weather conditions
• Soil conditions
• Weed species present, location and population
• Diseases present, location and population
• Insects present, location and population
• Crop damage
• Field map
• Results of scouting procedures performed
• Action required

Guidelines for Collecting and Submitting Plant, Insect Or Soil Material for Diagnosis or Identification

Remember that for disease diagnosis,
dead material is unsuitable

Choose plant(s) or plant parts showing representative symptoms.  If possible, send the entire plant, as well as more than one plant or plant parts, i.e. roots, leaves, etc.

Submitting Insect Specimens for Identification:
Dead, hard bodied insects should be sent cushioned in a sturdy container.  Soft bodied insects such as caterpillars, should be preserved in alcohol.

Hints for Shipping Insects:
Do not send insects in water. Do not tape insect to paper or send them loose in an envelope. Live insects should have sufficient food to survive until arrival. Clearly label the package with “live insects”.

If possible coordinate collection of sample with regular visit from seed corn company scout.

Hints for Shipping Plant Material:
Do not add moisture to plant(s) or plant parts. Wrap in newspaper (tying roots & soil off separately to reduce contamination) and put in a plastic container.

Avoid shipping over the weekend.

Soil and Root Sampling for Nematode Analysis:
Soil and root samples can be taken whenever the soil is not frozen. In Ontario, nematode populations are generally highest in May-June and again in September-October.

Samples from problem areas:
Soil and root samples should be dug from the margin of problem area where the plants are alive. For comparison, samples should be taken from healthy areas.

Sample Handling:
Place samples in a plastic container and clearly label with a waterproof marker or label.

Samples can be stored at 5-10 °C, but should not be exposed to extreme heat or be frozen.

It may be difficult to identify a pest or field problem, or you may require diagnosis and assistance. In these situations, send samples for analysis to diagnostic laboratories. For more information on how to take proper samples, where to obtain sample submission forms and diagnostic service fees, contact: