Sour skin disease of onion
Causal Agent: Burkholderia cepacia (syn. Pseudomonas cepacia)
- Field symptoms often appear as one or two leaves that have turned a light brown color.
- A watery rot develops at the base of the leaves and proceeds into the neck, allowing the leaves to be easily pulled from the bulb.
- As the disease progresses the outer bulb scales are infected.
- However, the outer most bulb scales and inner bulb scales may not become infected, which distinguishes sour skin from slippery skin where inner bulb scales are infected first.
- Infected scales develop a slimy pale yellow to light brown decay and may separate from adjacent scales allowing the firm center scales to slide out when the bulb is squeezed.
- Infected bulbs often have an acrid, vinegar-like odor due to secondary invaders, especially yeasts, colonizing decaying bulbs.
- The use of furrow irrigation, instead of overhead and recycled irrigation water, will reduce losses from this disease.
- Do not damage foliage prior to harvest or bulbs during harvest since B. cepacia enters the plant primarily through wounds.
- Onion crops should be harvested at maturity and the bulbs dried quickly.
- Storing onions at cool temperatures 0°C (32°F) with adequate ventilation to prevent condensation on the bulbs.
Submitted by krishnadubey on Thu, 16/08/2012 - 11:30