Effect of Spring Frost on Emerging Crops

Submitted by Anastasia Kubinec, Manitoba Agriculture, Oilseeds Crop Specialist

Originally posted May 8th and 30th, 2015…..re-post May 13, 2016.

Don’t assume because there is frost (or snow) on the ground, that your emerging crop in dead!

With the drop in temperatures in the past couple of days, there are a few things to keep in mind if the mercury dips below 0°C. The temperature is the instigator for causing frost, but whether it is -0.1°C or -4°C the damage inflicted is highly influenced on these other factors:

  1. Duration
    • Short frost = < 2 hours,  may not cause much damage if frost is light (above -1 to -2°C), crop type and staging is tolerant, conditions wet and crop has become acclimatized.
    • Short frost = < 2 hours, but hard frost (lower than -2°C), crops like canola are more sensitive to longer frost vs. cereals, damage can be variable in field and across area.
    • Long frost = > 2 hours, whether frost is light or hard the longer the negative temperatures the more time for damage to happen.  Tolerance by crop type varies.
  2. Other Environmental Conditions
    • Cloudy and wet – prior to a frost, cool temperatures slow plant growth and ‘hardens’ plants off, which will help them tolerate a frost.  Also wet soil helps buffer the cold air effects on the plants, as wet soils change temperature slower than dry soils.
    • Sunny and dry – The combination of a  dramatic drop in air temperatures when plants are actively growing then a brilliant sunny day after the frost event is where we have seen the most damage.  Scouting after the frost (24 and 48 hours) is very important though to assess extent and percentage of field injury.
    • Field trash cover – increased trash in fields was seen to increase frost damage on very susceptible crops in the 2009 June frost
  3. Crop Type
    • Spring Cereals – more tolerant than other crops types, can tolerant to temperatures as low as -6°C as growing point below ground until the 5 leaf stage.
    • Winter Wheat – can withstand very low temperatures for a short period of time (-11°C for less than 2 hours) up until the tillering stage.
    • Corn – smaller then V5, will recover from light frost as growing point below ground. Leaves probably will be killed, but plants will recover if the growing point ok.
    • Oilseeds – environmental conditions impact frost severity on susceptible canola and flax cotyledons. Resiliency increases at the 3-4 leaf stage (canola) or 2nd whorl (flax).  Sunflowers are fairly tolerant  up to the V4 stage.
    • Pulses – peas are most tolerant, then soybean, edibles bean are very susceptible even before emergence.   Field pea crops are rarely lost to frost. Soybean are more sensitive, but the smaller the soybean plant the more tolerant they are  – from emergence to cotyledon can withstand short light frosts.

Scouting After a Frost

Scouting should start 24 – 48 hours after the frost and continue for the 5 days following the frost event.  Look for leaves wilting, looking “water-soaked” or see “frost banding”.  Watch for new growth in the plant.  You do not want to see plants wilted and not perking back up or pinching off on the stem near the growing point (canola, flax, soybeans).  Also assess the area affected by frost, small areas or a few plants damaged are ok, as other plants emerged (or just emerging) will fill in those spaces.  Large dead areas may need to be re-seeded.

If in doubt of what look for, call your local agronomists, local FPE Specialist with Manitoba Agriculture or the Crop Industry Branch.

For more specific details on what actually occurs to plants with a frost and crop specific details and symptoms to look for (and how long after a frost to do assessment) see Manitoba Agriculture’s Spring Frost Damage Bulletin.

 

Respond
Have a follow-up question?

Yields Respectable in 2014 Despite a Challenging Year

Manitoba Agricultural Services Corporation (MASC) has released an early version of the 2014 yield report with 99.8% of the Harvest Production Reports (HPRs) keyed in.  The table below summarizes the 2014 average yield by crop type based on the harvested acres, as well as comparisons to 2013 and a 5-year average (2009 to 2013).

2014 yields

In February 2015, MASC will release their annual Yield Manitoba publication and update their Manitoba Management Plus Program (MMPP) website (http://www.mmpp.com/mmpp.nsf/mmpp_index.html) where further information on yields and acres by variety will be released.  Additionally, the data will be more complete in February as all HPR’s will be keyed in.

Submitted by:  Pam de Rocquigny, Anastasia Kubinec & Dennis Lange, Crop Specialist with MAFRD

Special Thanks to Doug Wilcox, MASC, for providing the 2014 data!

Respond
Have a follow-up question?

Swath, Desiccate or Let it Be – Field Peas & Cereals?!?

Prepared by Anastasia Kubinec, MAFRI Oilseed Specialist & Pam deRocquigny, MAFRI Cereal Specialist

With the cool, damp weather, crops are not maturing as fast as we would like.  ‘Stagey’ crops, big weeds (ragweed, buckwheat, kochia, redroot pigweed) and risks of weathering impacting quality have resulted in many calls about the differences/benefits of swathing, desiccating or letting the crop be.

First, go look at the crop again – how many stages is the crop at? Is it just low spots that have not turned? If the crop is starting to even up, you may want to leave it with the warmer temperatures coming this week (August 12-19, 2013) and let nature work for you. If the crop is at multiple stages and there are big weeds that will cause combine plugging, swathing, desiccating or pre-harvest weed control is a good management option.  For specific product information, contact the marketing companies for rates and registration details.

Key Notes:

  1.  Swathing or desiccating earlier than recommend (30% seed moisture) will not shorten the maturity of the seed. That is based on genetics and weather.  Performing these activities too early will result in reduced seed yield and quality.
  2. Glyphosate is not a desiccant- it is a pre-harvest herbicide and kills crops and weeds.  Use it for perennial weed control and not to desiccate the crop. Don’t use if crop is for seed use.
  3. Some product MRLs (Maximum Residue Limits) have not been set or are lower than what we can meet for crop export into other countries.  Be aware of marketing restrictions that may arise from using certain desiccants/harvest management tools.  For pulses see www.rayglen.com/pdf/2013%20Desiccant%20Guidelines%20for%20Growers.pdf.  For other crops, talk to you buyers.
  4. Know the weather conditions at application timing that will give the best results – Reglone works better on senescing plants and when temperatures are warm, Glyphosate works better on actively growing plants.

Field pea –Swath when most of the vines/pods are yellow-tan color and you can only barely leave a thumbnail impression. Desiccate when bottom 75% of pods are yellow with seeds firm and rattling in pods.  Desiccation usually eliminates the need for swathing and avoids the issues of wind-blown or rain-soaked swaths, and pick-up losses.  Decision to swath or desiccate will be based on weather forecast for the next 10 days, experience and machinery available.

Winter/Spring Wheat – Swathing timing and desiccation timing is the same – seed at 30% to 35% moisture, or hard dough stage (thumbnail imprint can barely be left in seed). Reglone and HEAT are not registered on any cereal crops for pre-harvest use.  If crop is intended for seed, using  glyphosate is not an option, so swath.  If not for seed and the weather forecast calls for wet conditions for the 10 days, glyphosate may be preferred versus swathing as the crop will weather better standing than in a swath.

Barley/Oat – Check  with your buyer about their policy on desiccants on the crop.  This may make the decision for you.  After determining this, the timing of swathing/desiccant is the same as wheat and the considerations to swath or desiccate are applicable as well.

For malting barley, maltsters want plump, mature kernels. The crop must not be swathed on the green side. Delay swathing until the heads have lost their green colour and have a moisture content of <30%. Swath around green patches to avoid having the sample from the field turned down because of green or immature kernels.   Keep in mind that wet weather may loosen the hull, reducing quality. Straight combining is becoming popular. Standing malt barley suffers less damage from moisture and dries faster. However, this benefit must be balanced against the increased risk of shattering losses. Six-row barley is more prone to shattering and neck-break than two-row barley.

 

Respond
Have a follow-up question?