Manitoba Insect & Disease Update – Issue 3: June 1, 2016

The Manitoba Insect and Disease Update for June 1, 2016 is now posted at: http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/insect-report-2016-06-01.html

SUMMARY

Insects: Cutworms and flea beetles on canola continue to be the insects of greatest concern. The cool, damp weather from the last few days would have slowed cutworm feeding, and the soil moisture, where not excessive, may help the plants compensate for feeding. Cutworm levels are quite variable, hard to find in some fields, more noticeable in others. So scout for potential cutworm feeding on emerging plants and dig for the larvae if you find an area that is showing signs of cutworm feeding. Precautionary insecticide applications, if cutworm levels are not economical, is not encouraged because of the potential damage to beneficial invertebrates.

Plant Pathogens: Rain has not only provided enough moisture for crops, but also for pathogens causing various crop diseases. Look for early signs and symptoms of diseases in crops. Scout! Scout! Scout!

Submitted by: John Gavloski, Entomologist & Pratisara Bajracharya, Field Crop Pathologist, Manitoba Agriculture

Visit the Insect Pages of our Manitoba Agriculture website at http://www.gov.mb.ca/agriculture/crops/insects/index.html
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Manitoba Disease & Insect Update – August 15th

A Manitoba Insect and Disease Update for the week of August 11-15, 2014 has been posted at: http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/insect-update-2014-08-15.html

Highlights include:

  • Grasshoppers continue to be a concern in some areas.
  • Lygus bugs should be scouted in canola in the late-flowering and early-podding stages.
  • Soybean aphid has been found in Manitoba, but only at very low levels.

Submitted by: John Gavloski, Entomologist & Vikram Bisht, Pathologist, MAFRD

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Manitoba Disease & Insect Update – August 8th

A Manitoba Insect and Disease Update for the week of August 4-8, 2014 has been posted at: http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/insect-update-2014-08-08.html.

Highlights Include:

  • Scouting for canola diseases has begun. Blackleg, root rots, white mold, aster yellows and alternaria pod blight will be surveyed.
  • Lygus Bugs in canola – The growth stage where canola has the most potential to have yield reduced by Lygus bugs is the early-podding stage.
  • In corn, scouting for Goss’s wilt and leaf blight disease will help growers understand the status in their crop. A few plants are showing common smut, which is not a serious disease.
  • Some have been asking about red mites seen on the wings of grasshoppers.
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Red mites on grasshoppers.

Submitted by: John Gavloski, Entomologist & Vikram Bisht, Pathologist, MAFRD

 

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Manitoba Insect & Disease Update – July 28 to August 1, 2014

A Manitoba Insect and Disease Update for the week of July 28-August 1, 2014 has been posted at: http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/insect-update-2014-08-01.html

Highlights include:

Pathology:

  • Fusarium head blight risk for wheat is moderate to low in different areas of Manitoba. Most of the wheat crops have finished flowering and thus at low risk. By end of the month, Fusarium head blight risk maps may not be needed.
Entomology:
  • Grasshoppers continue to be a concern in some fields.
  • Canola growers should be checking canola for Lygus bugs. Lygus can potentially be of concern when they feed on the pods of canola if levels are high, although feeding to flowering crops is not likely to be economical as canola has a very good ability to compensate for damage to flowers, especially when soil moisture is good. So far Lygus levels appear to be below economic levels in canola, with a few exceptions in the Eastern part of Manitoba.

Note: For those monitoring traps for bertha armyworm, the traps can be removed after you do your counts this week. We have enough weeks of data to know what the regional risks are. Overall trap counts in Manitoba were quite low this year. A map of the cumulative counts, as of July 28th, is posted in the update, and risk maps are also posted at the following MAFRD website (the July 28th map will be posted tomorrow): http://www.gov.mb.ca/agriculture/crops/insects/bertha-armyworm-forecast.html

Submitted by: John Gavloski, Entomologist & Vikram Bisht, Pathologist, MAFRD

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Manitoba Insect & Disease Update – Week of July 21st to 25th

A Manitoba Insect and Disease Update for the week of July 21-25, 2014 has been posted at: http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/insect-update-2014-07-25.html

Highlights include:

Pathology:
  • Goss’s wilt and leaf blight disease are showing up in corn.

Corn leaf with well developed leaf blight of Goss’s Wilt disease. Photo: Vikram Bisht, MAFRD

  • Ergot disease infection is now showing up in fall rye and grasses.
  • Blackleg infection on lower stems/roots on canola is showing up.
  • Downy mildew on sunflowers is reported.
Entomology:
  • Grasshoppers are starting to mature to the adult stage. How much they move into crops from surrounding vegetation may partially depend on how lush the roadside vegetation remains relative to the crop.
  • Still no soybean aphids found in Manitoba in 2014.

Submitted by: John Gavloski, Entomologist & Vikram Bisht, Pathologist, MAFRD

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Manitoba Insect & Disease Update – Week of June 30 to July 4

A Manitoba Insect and Disease Update for the week of June 30 to July 4, 2014 has been posted at: http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/2014-07-02-insect-update.html

  • Information is provided on the potential effects of flooded fields on grasshoppers and wireworms.
  • Brown spot and bacterial leaf blight have been occurring in some soybean fields; risk of Fusarium head blight in cereals is high to extremely high.
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Brown spot disease on lower leaves of canopy. Photo courtesy: Vikram Bisht, MAFRD

  • Forecasts for emergence of wheat midge and a key parasitoid of wheat midge are provided.

Submitted by: John Gavloski, Entomologist & Vikram Bisht, Pathologist, MAFRD

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Manitoba Insect & Disease Update – Week of June 16th

A Manitoba Insect and Disease Update for the week of June 16-20, 2014 has been posted at: http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/2014-06-17-insect-update.html

Highlights include:

  • Cutworms continue to be an issue in some areas.
  • Flea beetle populations remain a concern in some areas, although the cool weather and advance of many canola fields to stages more tolerant to feeding has resulted in decreased damage.
  • Grasshoppers are emerging, but generally still in the first and second instar stages.
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Juvenile grasshopper (left) and non-economical species of leafhopper (right) (MAFRD)

  • Alfalfa weevil larvae are starting to be noticed in some alfalfa fields.
  • Brown spot (Septoria) and bacterial leaf blight have been observed in soybeans.
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Early stage of bacterial blight spots and brown spot disease on unifoliate leaves of soybean (MAFRD)

Submitted by: John Gavloski, Entomologist & Vikram Bisht, Pathologist, MAFRD

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Manitoba Insect & Disease Update – Week of June 9 to 13th

A Manitoba Insect and Disease Update for the week of June 9-13, 2014 has been posted at: http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/2014-06-10-insect-report.html

HIGHLIGHTS INCLUDE:

Current Insect Scouting Priorities

  • Flea beetles: Foliar spraying, in addition to the seed treatments, is occurring in many areas.
  • Cutworm: Dingy and redbacked cutworms seem to be our dominant species.  How long will they feed? Will crops compensate for some cutworm feeding?
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Dingy Cutworm

  • Check field edges to assess levels of emerging grasshoppers.

Insect Monitoring Update

Diamondback Moth: It is likely that we had a moderate population of diamondback moth blow into some areas of Manitoba.  Weekly maps for the monitoring program for diamondback moth can be found at: http://www.gov.mb.ca/agriculture/crops/insects/diamondback-moth-monitoring.html

Submitted by:  John Gavloski, Entomologist & Vikram Bisht, Field Crops Pathologist, MAFRD

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Manitoba Insect & Disease Update

Summary

  • Insect and disease activity continues to be low on crops in Manitoba.
  • The cool temperature has slowed the emergence of many insects.
  • There is no evidence to date of any major movement of insects that get blown into Manitoba form the southern U.S., such as diamondback moth and aster leafhopper.

The update provides information on the following topics:

Grasshoppers: When will emergence likely start? Degree day models can be used to forecast anticipated dates of emergence for these pest species. Based on such models it will likely be early-June before we see a start to the emergence of these species of grasshoppers in most areas.

Recent Rain and Grasshoppers? The recent rains will likely do very little to negatively impact the survival of our pest species of grasshoppers.

Insect Monitoring Programs.  Updates on diamondback moth, wireworms & cutworms.

The complete Manitoba Insect and Disease Update for May 21, 2014 with additional information on the above topics has been posted at: http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/2014-05-20-insect-update.html

Submitted by:  John Gavloski, Entomologist & Vikram Bisht, Plant Pathologist, MAFRD

 

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Four Early-Season Insects to Look For

Cutworms

  • There are different species, which will affect crops differently and may be present at different times.
  • Dingy cutworm overwinter as partially grown larvae, so will be ready to feed as the crop emerges. They will feed on emerged plant tissue, but don’t do a lot of clipping of stems.
  • Redbacked cutworms overwinter as eggs, so may not be noticed until later in May or June, when larger larvae are feeding on plants. They potentially will clip stems.
  • Cutworms can be patchy in a field. Areas of the field that had later flowering crop or weed patches last year may have higher levels of cutworms.
  • Cutworms are nocturnal, feeding during the night, then burrowing into the soil during the day. They will burrow deeper if the soil is dry.
  • If insecticides are needed to control cutworms, they should be applied as late in the day as practical, and may only be needed on patches, depending on how the population is distributed in the field.
  • More information on cutworms can be found at : http://www.gov.mb.ca/agriculture/crops/insects/cutworms-field-crops.html

Flea beetles in canola

  • The 2 main species of flea beetles in canola in Manitoba are the striped and crucifer flea beetles.
  • These are potentially a concern from the time canola emerges until about the 3 to 4 leaf stage in canola.
  • Seed treatments will provide early season control. None of the seed treatments currently registered work as well under cool, wet conditions as they do in warmer, drier conditions.
  • Insecticide effectiveness can vary with the species of flea beetle. Neonicotinoid-based seed treatments (Helix, Prosper) work well against crucifer flea beetle, but control will be less on striped flea beetle. This is not a developed insecticide resistance, just natural variation in effectiveness between species.

Wireworms

  • Are larvae of click beetles. Will have 3 small pair of legs at the front the body, but don’t have the fleshy prolegs at the back like cutworms.
  • Feeding is all underground.
  • Foliar insecticides will not be effective.
  • Seed treatments can stop wireworms from damaging young crops, however current seed treatments result in little mortality of the wireworms.
  • Are hard to monitor; bait balls can be used, but growing vegetation and other sources of CO2 near a bait ball will compete for wireworms and reduce effectiveness.
  • Practices that result in quick germination and early growth can help minimize damage form, wireworms.
  • More information on wireworms, as well as some insects that could be confused with wireworms, can be found at: http://www.gov.mb.ca/agriculture/crops/insects/wireworms.html

Grasshoppers

  • It will probably be early-June before we see much hatch of our potential pest species of grasshoppers this year.
  • Any larger grasshoppers seen in May will not be pest species.
  • Heavy rains and standing water will not kill grasshopper eggs. Newly hatched grasshoppers, however, are quite susceptible do being killed because of heavy rains. So heavy rains in April or May will likely do little to our pest species of grasshoppers. Heavy rains in June could potentially reduce populations significantly.
  • Areas that had lush green vegetation late last year, such as along field edges, are more likely to have higher concentrations of grasshopper eggs, and early-season grasshopper levels will be heaviest in these areas. These areas should be monitored in June.
  • If grasshopper control is needed:
    1. Control of young grasshoppers is more effective than controlling adults
    2. Control may only be needed along field edges or areas where they are concentrated early.
    3. Bran baits (with an attractant that lures the grasshopper to the bait) as well as foliar sprays are available.

Submitted by:  John Gavloski, MAFRD Extension Entomologist

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