Time to Start Scouting!

The crop is barely in the ground, yet it's already time to start the scouting program. The key to successful crop problem diagnosis is timely troubleshooting!

There is no substitute for walking your field! Take time to walk each field individually. Look for things that will affect yields, such as crop emergence, plant population, missing or unhealthy plants, weed escapes, herbicide injury, insect damage, etc. Check the fields often during the first two months after planting.

Crop scouting should be kept simple, but it must provide accurate information. Basic field scouting equipment should include field maps, shovel, pocketknife, plastic "treasure" bags to collect specimens, hula-hoop for population counts and a clipboard with field scouting data forms like the one included in this newsletter or notebook for record keeping.

The scouting pattern must be representative of the whole field!

• Include changes in variety / hybrid, soil type, past cropping history, fertilizer/ manure application and any other factors, which can affect plant growth.
• The pattern should cover all parts of the field, and should vary each time the field is scouted.
• 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 metres into a field. Outside rows and headlands should not be included in the scouting pattern unless there are specific reasons for sampling these areas.
• For uniform pests, or problems for which the distribution pattern is not known (eg corn rootworm, stalk rots, weeds), the sampling locations should be evenly distributed across the field.
• For problems expected to occur on headlands or in outside rows (eg armyworm, spidermites or soil compaction), the sampling locations should be evenly distributed around the edges of the field.
• For problems expected in particular parts of a field (Phytophthora Root Rot in damp clay soils or black cutworms in weedy patches), sampling locations should be concentrated in areas where the problem or pests are most likely to be found.

Plant population in row crops can be calculated by counting the number of plants in 1/1000 of an acre and then multiplying the count by 1000 to obtain the number of plants per acre. Table 1 below lists the row length equal to 1/1000 of an acre at various row widths.

To determine plant population in narrow row crops and pest infestation levels, a sampling frame with a known area can be placed on the ground for the counts. This can be accomplished using a square frame (e.g. 50 cm x 50 cm equal 0.25 m²) or circular frame (e.g. a Hula-hoop). The hula-hoop method is displayed in Table 2. By using the table, the number of plants per acre can then be determined by measuring the diameter of the hoop, counting the number of plants that are found within the hoop and multiplying that by a predetermined factor listed. For replant decisions in soybeans, Table 3 may be simpler.

(1) 100,000 plants/acre is 60% of a full stand. A healthy even stand of this population has 95 to100% of the yield potential of a full stand.

(2) At 70,000 plants, a healthy, even stand has 80%-85% of the yield potential of full a stand.

Regardless of the method used to determine plant population and pest infestation levels, at least 10 random counts should be taken in each field to determine an average.

| Top of Page |