What are these “eggs” on cereal heads in my field?

Quite a few people over the past week have sent in photos (as in Figure 1 below) asking what are these “eggs” on the cereal heads, and noticing that they can be quite abundant in some fields.

Parasitoid Pupal Cases

Figure 1. Pupal cases of a wasp parasitic to armyworms. Photo from Dean McCowan, Agree Ag Services.

These are not eggs, but are the pupal cases of parasitic wasps. These are being found in fields that contained armyworms, and it is likely that armyworms were hosts for the parasitoids. For some parasitoids it is common for dozens of parasitoid larvae to emerge at the same time from an individual armyworm, killing it in the process. This is because an initial egg laid in the armyworm starts dividing and can become dozens or at times hundreds of eggs, that results in multiple parasitoid larvae of the same general age feeding in the armyworm. When the parasitoids emerge form the armyworm, they all emerge at approximately the same time, and very soon after form these clusters of pupal case, which are together in a cluster on the plants. So each cluster would have been parasitoids form a single armyworm, and will result in multiple wasps looking for more caterpillars to parasitize.

Information by:  John Gavloski, Entomologist, MAFRD

This article was taken from the Manitoba Insect & Disease Update: July 14, 2015.  For the complete issue, please visit MAFRD’s website at http://www.gov.mb.ca/agriculture/crops/seasonal-reports/insect-report-archive/insect-update-2015-07-14.html

 

 

 

 

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Improving Greenfeed Success When Seeding Late

Annual crops are a late season seeding option when used for livestock feed or ground cover. They can be grazed within four to six weeks of planting thus providing rest and recovery for your pastures or harvested as greenfeed or silage for winter feed. Generally planting prior to July 1 will ensure most crops will reach the optimum harvest stage for greenfeed or silage production. However in the event that you are not able to seed as early as desired, find in the attached article some considerations that will help you improve yields and quality.

IMPROVING GREENFEED SUCCESS WHEN SEEDING LATE

There are also multiple articles on MAFRD’s website on greenfeed and annual crops to increase feeding flexibility:

For further information, contact your GO representative.

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Sandblasting Injury in Cereals & Corn

On May 29th, there were extremely windy conditions in some areas of Manitoba.  The strong winds may result in sandblasting injury in young and emerging cereal and corn crops.  Sandblasting injury is caused by winds impacting soil particles against the plant leaves.  Light, sandy soil areas are the most common areas of sandblasting in a field.

Symptoms include:

  • Small abrasions on leaves caused by blowing sand, which are often copper-tone in color
  • Shredding of leaf tissue, making them prone to desiccation
  • Plants may be cut off at the soil surface in severe cases.

In cereal crops the growing point remains below ground until approximately the 5-leaf stage, so if only leaves are affected the plant should recover.  In corn, the same principle applies.  The shredding of exposed leaves is not likely to cause substantial yield loss because the growing point in corn remains below ground until the V5 growth stage.  For cereals and corn, favorable weather will promote development of new leaf growth, so the recent rainfall will help.  However, if the growing point in either crop type has been impacted, reduced stands will likely result.  So the key is to keep scouting for the next few weeks to assess the full impact.

Goss’s Wilt in Corn

In corn, another point to keep in mind is plants that are damaged by hail, wind, or sand-blasting are susceptible to Goss’s Wilt infection as the bacteria can infect corn throughout the growing season and can enter through the wounds caused by sand-blasting.

As you are scouting for Goss’s Wilt throughout the season, focus your attention on fields that are:

  • planted to a Goss’s susceptible hybrid,
  • have a history of Goss’s Wilt,
  • have surface corn residue, and
  • may have been injured by severe weather.

Initial symptoms of Goss’s Wilt include water-soaked lesions on the leaves later accompanied by “freckling”. Bacterial ooze may also occur on the lesion, giving it a wet or greasy appearance. When the ooze dries, it leaves a shiny residue on the surface of the lesion.  More information and photos can be found at: http://www.gov.mb.ca/agriculture/crops/miu/2012/2012-08-24/report.pdf

Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist

 

 

 

 

 

 

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Impact of Hail in Cereal Crops

Originally Published September 3, 2014

Impact of hail on cereal crops will depend on growth stage of the crop at the time of the hail event and the severity of damage.  In a study by R.H. Busch in North Dakota in wheat, the greatest yield reduction resulted when stems were broken in the milk stage, followed by anthesis, soft dough, boot, and hard dough stages – see Table below (Busch, 1975).

Grain yield reduction in spring wheat with 100 percent of stems bent.
Growth stage Yield reduction (%)
Boot (Zadoks 45) 28 to 39%
Anthesis (Zadoks 65) 15 to 60%
Milk (Zadoks 75) 30 to 70%
Soft dough (Zadoks 83) 16 to 55%
Hard dough (Zadoks 87) 3 to 47%
Table derived from Busch, 1975

 

Yield losses can also be directly attributed to shattering of the mature crop.  A simple and rough estimate of grain loss requires the use of a one-foot square frame:

  1. Pick a typical area of the field.
  2. Place a 1 ft by 1 ft (inside dimension) box on the ground and count the kernels found within the box.

A one (1) bushel per acre loss equates to 20 wheat kernels per/ft2, 14 barley kernels/ft2 and 10 oat kernels/ft2.  Keep in mind that this is a ‘fudge factor’ but for the purpose of rough field estimation is an adequate estimate.

Remember to please contact your hail insurance provider for their procedures in assessing hail damage as they may be different than what has been provided here.

Source:  Busch, R. H. 1975.  The effect of simulated hail injury on spring wheat. North Dakota AES Bulletin 497. 18 pp.

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, MAFRD

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What is the impact of hail to yield of cereal crops?

Impact of hail on cereal crops will depend on growth stage of the crop at the time of the hail event and the severity of damage.  In the article “Hail Damge in Small Grains” by Joe Lauer, Universityof Wisconsin, it states before jointing, small grains are least susceptible to hail damage. The spike is still below ground and protected from injury.

In a study by R.H. Busch in North Dakota in wheat, the greatest yield reduction resulted when stems were broken in the milk stage, followed by anthesis, soft dough, boot, and hard dough stages – see Table below (Busch, 1975). 

Grain yield reduction in spring wheat with 100 percent of stems bent.
Growth stage Yield reduction (%)
Boot (Zadoks 45) 28 to 39%
Anthesis (Zadoks 65) 15 to 60%
Milk (Zadoks 75) 30 to 70%
Soft dough (Zadoks 83) 16 to 55%
Hard dough (Zadoks 87) 3 to 47%
Table derived from Busch, 1975

Source:  Busch, R. H. 1975.  The effect of simulated hail injury on spring wheat. North Dakota AES Bulletin 497. 18 pp.

Remember that estimating yield loss due to hail is only an estimate.  The remainder of the growing season will help determine final yields.  Please contact your hail insurance provider for their procedures in assessing hail damage as they may be different than what has been provided here.

Submitted by:  Pam de Rocquigny, MAFRI Cereal Crops Specialist

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Banded nitrogen with wide spaced seed rows

Question from a Subscriber of Crop Chatter:  I’m setting up a triple shoot air drill with wide (12.6 inch) spaced seed shanks. Each seed shank has a 3.5 inch paired row seed opener with a granular fertilizer placement tube to put granular fertilizer in the center of each paired row. Additionally, the drill has mid row banding shanks on 25.2″ spacing to apply NH3. I have a 3 compartment air tank.

For cereals, I will place the seed and phosphorus together through the paired row openers, with starter urea placed in the middle of each seed row through the granular fertilizer tubes. For canola, the seed and phosphorus will be placed together with ammonium sulphate (and possibly some urea if a fertilizer blend is used) in the center of each seed row. For soybeans, the seed and granular innoculant will be placed together and phosphorus will be placed in the seed row centers. NH3 will be applied for cereals and canola through the mid row shanks with 1″ openers. The NH3 will therefore be up to about 7″ away from the furthest placed seed.

I’m trying to determine how to best split the total nitrogen rate between urea and NH3. Since NH3 is cheaper and less handling than urea, my preference is to maximize NH3 use. Given that I have heavy clay soil:

1) How long it will take the furthest away plants to be able to access the NH3?
2) How much urea should be applied to keep the crop well suppied with nitrogen until all plants can access the NH3 band?

Answer (provided by John Heard, MAFRI Soil Nutrition Specialist)

Crop roots access nitrogen in mid-row bands in 2 ways:  roots growing  laterally can intercept the band and mid-row placed  ammonia converts to nitrate-N which then migrates as roots consume soil moisture.  Usually mid-row banded nitrogen is available for crop growth by the time it is needed.  Your seed-placed phosphorus fertilizer usually contains nitrogen to keep the seedling nourished.  But we hear on occasion that early season crop yellowing (MN deficiency?) is observed in the situations here – cool, heavy clay soil with wide spaced mid-row bands.  In years with warm, moist or dry soils, root access to bands will likely be quicker than this year.  Fortunately you have an option to place some urea in a band close to, but safely away from the seed.  I should think no more than 10-20% of the nitrogen requirement needs to be supplied there.

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