Disease of the Month - Heat / Drought related Deformities

 
  Hort Snacks - July 2018
Download 505K pdf file ("HortSnacks-July2018.pdf")PDF
(505K)
     Subscribe to our free E-Newsletter, "Agri-News" (formerly RTW This Week)Agri-News
This Week
     Hort Snacks HomeHort Snacks Home
 
 
 
 Crops Affected: range of crops (depending on disorder)

Symptoms / Conditions Favouring Development:

Hollow Heart (potatoes)

  • Common in oversized or rapidly growing, early tubers
  • Very dependent on cultivar
  • Most severe under rapid tuber growth conditions
    • Uneven moisture (dry followed by wet) or fertility
    • Wide plant spacing or missing plants
  • No visible external symptoms
  • Internal symptoms – tan to brown walled cavities that develop from brown areas at or near the centre of tubers
Hollow Stem (broccoli and cauliflower)
  • No visible external symptoms
  • Small cracks occur internally, which coalesce to form a hollow central stem
  • Cause is suggested to be related to plant nutrient balance, as well as growth conditions after head initiation
Forking (carrots)
  • Cause can be a result of disease or pest damage, compacted or heavy soils, excessive plant densities, or other factors that damage the root tips
  • Location of the fork can give an indication of when the damage occurred and may suggest probable cause
Growth Cracks (carrots, rutabaga, turnips, potatoes, cabbage, tomatoes, cherries)
  • Rapid tissue growth leads to vertical cracking, with cracks varying in size
    • Cracks may originate along root or tuber or in neck areas
    • Older cracks may have a layer of rougher wound tissue over the inside of the crack
    • More typical on larger roots
  • Fruit cracking can occur as radial or concentric cracks
    • Can occur as “bursting” when very rapid
  • Is typically the result of fluctuating soil moisture levels, specifically when abundant moisture follows a dry spell
Jelly End Rot (potatoes)
  • Most prevalent in Russet Burbank potatoes
  • Stem end tissues of tubers become glassy, jelly-like and shrivels and dries up
  • Favoured by high soil temperatures and dry conditions followed by excellent moisture
  • Often associated with misshapen tubers
Brown Bead (broccoli)
  • Buds of broccoli florets turn tan or brown and can fall off easily
  • Associated with rapid growth in high temperatures following abundant moisture
Sunscald (various crops)
Bulb crops
  • Soil level tissues shrivel, and the plant withers and dies
  • Young, sensitive plants are damaged by hot, sunny conditions in dry springs
Beans / Fruit crops (e.g. tomatoes)
  • Small, water-soaked spots on plant parts only on exposed sides of the plant, typically in intense, direct sunlight following cloudy, high humidity and high temperature conditions
  • Spots become brown to white and grow together to form large necrotic lesions; may be sunken
Management:
  • Maintain adequate (and uniform, if possible) moisture levels throughout the growing season
    • This may involve the use of irrigation, improving soil moisture hold capacity, etc.
  • Ensure plants are uniformly spaced within the row
  • Avoid excess or inadequate fertilization (particularly nitrogen)
  • For some disorders (e.g. hollow heart / hollow stem), there are varietal differences in susceptibility
  • If possible, adjust planting dates to avoid having susceptible stages present during hot, dry conditions.
  • Avoid irrigation to ripe fruit (susceptible to cracking)
 
 
 
 
Share via AddThis.com
For more information about the content of this document, contact Robert Spencer.
This information published to the web on June 26, 2018.