A Year in Review: 2001 Pest Problems Across Manitoba

Transcription

1 22 A Year in Review: 21 Pest Problems Across Manitoba David Kaminski, Soils & Crops Branch Manitoba Agriculture & Food, Carman, MB RG J (dkaminski@gov.mb.ca) Our individual perspectives on the impact of pests and other constraints to crop production are strongly influenced by where we live and work. Regional reporting on such issues may zero in on one or two key constraints while localized problems may escape the notice of those dealing with the same issues elsewhere. Objective The objective of this review is to capture the diversity of pest management problems that agronomists face, to examine regional differences, and to compare our individual experiences with the findings of surveys that try to measure the impact of those constraints. Methods Registrants were asked to come up with their own top three Diseases, Insects, Weeds and Environmental Constraints to crop production in the areas in which they operate. The results were compiled and are presented alongside studies with provincial scope. A 1 st ranking was scored as 3 points, a 2 nd place as 2, and a 3 rd as 1. All responses were then added to obtain a cumulative score for each major pest problem. Environmental constraints are not presented here but were discussed in one of the evening Bearpit Sessions. They can also be examined in the raw data on this spreadsheet [link]. Results Fifty-seven participants at the 21 Manitoba Agronomy Conference (MAC) contributed their opinions through the mail-in survey. Of these 53 were from Manitobans and each geographic region was represented although for the regional comparisons there were sufficient responses from only the Southwest (), Central (22) and Eastern (9) regions. For the overall scoring, all responses were included. Some respondents did not report any weed (2), insect (), or environmental constraints (). Diseases There were two clear choices among the top 6 diseases: (FHB) of wheat and other cereals and white mold (Sclerotinia) affecting, primarily, canola and beans. FHB came nearest to the maximum possible cumulative score (171 = 57 x 3) with a score of 11. While the top two diseases were consistent from region to region, there were some differences in the other notable diseases. For example, potato late blight was ranked third in the central region while blackleg of canola was not a concern in either the eastern or southwestern regions. Weeds Among the top weeds, wild oats was the highest ranked scoring out of a possible maximum cumulative score of 5. Ranked 2 nd and 3 rd were and wild buckwheat. Some respondents pointed out that perception of weeds as problems was not necessarily related to abundance but also to the investment in management and the concern with herbicide resistance. This may be why wild oats and placed 1 st and 2 nd in this survey but were ranked 2 nd and th in the most recent provincial weed survey. Interestingly, green foxtail ranked only th in this survey even though it has been listed as by far the most abundant weed in Manitoba fields in the past three weed surveys., a plant that is a known indicator of salinity, was th overall and was mentioned in each of the regions but ranked 3 rd in the southwest., similarly, appeared in all regions but ranked th in the central region. Some, but not all, respondents singled out herbicide tolerant volunteer canola as

2 23 their concern. Curled dock, while not making the top overall, was ranked 2 nd in the eastern region a reflection of the overabundance of moisture throughout most of that part of the province. Insects There was great diversity in the insects that made the top 1 overall, as well as tremendous regional variation in their ranking. In fact, the top-ranked pests were different in each region: on canola and sunflower ranked 1 st in the eastern region, wheat midge was 1 st in the southwest, and flea beetles and aphids tied for top spot in the central region. Furthermore, in the central region three of the top six pests attack sunflower (sunflower beetle, banded sunflower moth and ), reflecting the importance of the crop to that region. Diamondback moth ranked 2 nd overall but did not make the top 1 in the central region. This is surprising since numbers in the central region were high and a significant area was sprayed for diamond back. Another canola pest believed to be on the increase, bertha armyworm ranked th overall but 2 nd in the southwest. was a concern in both the central and southwest regions. The last two insects to appear in the top 1 were true armyworm and grasshoppers. Conclusions How do the views of field agronomists stack up against the findings of field studies of provincial scope? Very well, it seems, when it comes to disease issues. The major issue that MB grapples with in field crop diseases is. Manitoba Agriculture and Food, through its ARDI funding, is obviously devoting resources in the right direction. The regional impact of FHB has been documented on an annual basis by Dr. Jeannie Gilbert and others at the Cereal Research Centre (AAFC) in Winnipeg. These findings are reported in the Canadian Plant Disease Survey and can be found on the website of the Canadian Phytopathological Society. ( In 2 and 21, these surveys, conducted on crops as they mature, aligned well with the FHB risk forecast produced by ACE a MB-based environmental monitoring agency. They also align well with harvest survey data, compiled by Dr. Randy Clear, mycologist with the Canadian Grain Commission, and posted on their website. ( Despite the limited number of responses to the pest survey from the MAC, the data on the impact of FHB is consistent with the aforementioned studies. FHB was especially intense in the Interlake region and a minor concern in the Northwest. For a validation of the concern with Sclerotinia we find agreement in the disease component of a canola rotation study conducted by Dr. Debbie McLaren (AAFC, Brandon) and collaborators, reported annually in CPDS (see above). In 21, the survey examined 277 canola crops and found stem rot caused by Sclerotinia sclerotiorum to be the most significant disease in all regions of Manitoba. Again, the pest survey from the MAC aligns well with Debbie s data: The two who responded from the northwest ranked sclerotinia 1 and 2 of the 71 fields in the NW very few (6 or <1%) escaped infection. By contrast, in the eastern region where it was so wet, there were proportionally more fields that escaped sclerotinia infection: 26 of 6 or 56%. MAC pest survey respondents consistently ranked sclerotinia 2 nd in importance to FHB in the eastern region. Time and space limit the discussion of the validity of this kind of survey to diseases. Suffice it to say that there are many more players on the field when it comes to weeds and insect pests. Thanks to Dr. Todd Andrews, provincial weed specialist, and Dr. John Gavloski, provincial extension entomologist, for additional comments and review.

3 2 53 MB responses Pest Management: 21 in Review 2 1 st rank scores 3 Manitoba Agronomy Conference December 1, 21 2 nd rank scores 2 David Kaminski, MB Agriculture & Food rd rank scores 1 Top 6 Diseases Top 6 Diseases - Eastern Rust Septoria Top 6 Diseases - Southwest Top 6 Diseases - Central Septoria Rust (incl OCR)

4 25 Top Weed Concerns Top Weeds - Eastern Cleavers 6 2 Curled dock Top Weeds - Southwest Top Weeds - Central 2 3 Cleavers Thistles (various) 2 1 Thistles (various) Millet (foxtails) Top 1 Insect Pests Top 1 Insects - Eastern Bertha armyworm Alfalfa looper European corn borer

5 26 Top 1 Insects - Southwest Top 1 Insects - Central 2 2 Bertha armyworm Cutworms Your Rankings st 2nd 3rd Portage Winnipeg 21 MB Canola - Sclerotinia %DI no. of fields > E C SW NW