Weird podding? Hormone response to drought and heat most likely

August 8, 2019 - Issue 19

Canola is not a heat-loving crop, and many areas of the Prairies were quite hot while canola was flowering. Heat during flowering (28°C or more coupled with warm nights) can cause flower abortion (missing pods) or small dead pods. Heat can also cause a hormone response that can result in misshapen pods. Specific symptoms can include bloated pods without seeds or with seeds that may show precocious germination inside the pod. This can lead to pod splitting and germination with unusual growth of flower parts. Even with just a few days of heat, canola plants may require a week for hormone balance and regular pod formation to return. Heat-related symptoms are usually localized in a field (particularly around knoll tops and sandy areas). Check your weather records for highs and (important) overnight lows.

These look like heat-damage pods but the cause is not always clear.

Aster yellows can cause bladder-like pods and various other strange growth symptoms. Damage is usually sporadic throughout the field and reports of aster yellows are low so far this year. Some labs on this list can test for aster yellows phytoplasma.

Aster yellows. Source: Keith Gabert
Sulphur deficiency symptoms. Credit: Justine Cornelsen

Sulphur deficiency can also cause short pods with little or no seed set. Other S deficiency symptoms include stunted growth, light-coloured leaves on newer leaves vs older leaves, purpling and cupping on stem leaves during bolting, and pale, smaller flower petals, especially on hill tops. What is the field’s sulphur situation? Soil tests in the problem areas can help with diagnosis.

If these don’t seem likely, consider some of the other factors that can cause flower abortion and missing pods.

Canola Watch