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Integrated Pest Management and the Idaho Potato Industry -- Results of Grower Surveys

INTRODUCTION

We assessed pest concerns and use of IPM practices within the Idaho potato industry by conducting a statewide survey of commercial (non-seed) growers during winter 1997-1998. Our objectives were two-fold: 

1. to identify grower perceptions of key pest problems in potatoes; 

2. to measure use of pest control tactics by commercial potato producers, especially use of pesticides and their alternatives.

The survey was part of an overall effort by the University of Idaho Extension IPM Program to document use of pest management methods by key agricultural industries in Idaho.

Ten University of Idaho faculty contributed to survey questionnaire design. We deliberately incorporated questions from the May 1997 draft version of the National Potato Council "IPM protocol" point system for scoring rates of IPM adoption among potato growers. The questionnaire was mailed to 500 randomly-selected commercial potato growers during late December 1997. Follow-up postcard reminders were mailed to persons who did not return completed questionnaires with 2-3 weeks of the initial mailing. Persons who did not respond to the postcard reminder received a second copy of the questionnaire 4 weeks later. Results here summarize 123 completed surveys.

PART 1. DEMOGRAPHICS OF SURVEY RESPONDENTS 

• The typical survey respondent farmed approximately 2,000 acres annually. Average yearly potato production ranged from 250 to 500+ acres planted, virtually all of which was Russet Burbank grown under sprinkler irrigation. On average, survey respondents were young-to-middle-aged, well-educated, and reported gross farm sales in the $250,000 to $500,000+ range during 1997 (TABLE 1). 
• To the extent these respondents represent the "typical" commercial potato grower in Idaho, survey data here can be taken as a measure of industry as a whole.

PART 2. GROWER PERCEPTIONS OF POTATO PEST PROBLEMS

• Commercial potato growers perceive the relative importance of diseases & nematodes, weeds and insect pests as nearly equal (TABLE 2); 33% to 39% of survey respondents ranked these pests as "serious" problems. A slightly higher percentage (10.6%) said diseases and nematodes were "not a problem," compared to 3.5% who said weeds and insects were "not a problem."
• Perceptions of pest importance during 1997/98 increased 3-fold from values reported in 1992 statewide surveys, when only 10% of commercial potato growers in Idaho considered these pest groups as "serious problems."
• The majority of potato producers said that rodents are not problems in their potato production (TABLE 2).
• Growers reported their 3 most important pest problems in potatoes were late blight, annual broadleaf weeds and green peach aphids (TABLE 3); approximately 40% - 50% of survey respondents ranked these as "serious."
• Growers generally perceive individual disease problems as more serious than individual weed or insects pests; leafroll, early blight and Verticillium were ranked by more than 25% of growers as "serious" problems.
• Pests ranked as "not a problem" by a majority of growers were:

• Essentially all commercial potato growers in Idaho practice certain elements of IPM. Multiple pest control tactics are the norm, rather than reliance on pesticides.
• "Good farming" cultural practices are widely used to control potato pests, especially diseases (TABLE 4).
• Use of biological controls is limited to field scouting for beneficial natural enemies of insect pests and use of reduced insecticide application rates to reduce harm to beneficials (TABLE 4). The percentage growers who reported they never used the biological control methods noted in the National Potato Council "IPM protocol"
  was as follows:

• Growers rely on programs of field scouting, pest forecasting and economic thresholds to determine the need for pesticide use targeted against all the major pest groups (TABLE 4). Adoption rates of IPM sampling and decision-aids have increased modestly since the 1992 statewide survey.

PART 3B. IPM PRACTICES - pesticide use patterns

• Pesticides remain an integral part of potato pest control (TABLE 5). Nearly all commercial potato acreage in Idaho is treated with herbicides, fungicides and insecticides; 3 in 4 fields are treated with soil fumigants.
• Potato growers seldom make repeated pesticide applications to the same field during the growing season (TABLE 5). An exception is fungicide applications for late blight, where 75% of Idaho's commercial potato acreage receives 4 or more sprays each season. Multiple applications of foliar insecticides for aphids and Colorado potato beetles doubled since the 1992 statewide survey from 10% fields treated at least twice annually with foliar insecticides to approximately 20% fields treated at least twice.

PART 4. CONCLUDING (PRECAUTIONARY) NOTES ABOUT THESE DATA

• Survey sample size is relatively small, but production system characteristics suggest our sample population of growers is in fact representative of commercial potato producers in Idaho.
• Data here is growers subjective perceptions of pest importance and not necessarily an objective measure of actual economic impact; nonetheless, grower beliefs about pest status and attitudes about pest control needs are critical if we are to conduct research and extension programs that fit the way farmers produce potatoes in Idaho.

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