Internal Browning of Brussels Sprouts (Centre Rot)

Internal sprout leaves discolour and rot. The problem is most severe on large and/or overmature sprouts at the bottom of the stalk. The cause is believed to be a lack of calcium in the developing sprouts brought on by stressful environmental conditions. Crops on sandy soils are more susceptible than those on loams or clay loams.

Control

1. Lime to maintain soil pH over 6.0.
2. Do not promote excessive growth by over fertilization with nitrogen.
3. Avoid moisture stress while sprouts are sizing.
4. Harvest before sprouts are over mature and/or oversize.

Premature Head Formation

Small heads are formed before plants have enough leaf area to support the development of marketable size heads. Premature head formation usually occurs when transplants are exposed to stress after being set in the field. Early varieties are most susceptible.

Control

Do everything possible to ensure rapid crop establishment and growth after transplanting.

1. Do not use old, oversize or overly hardened transplants.
2. Ensure soil fertility is adequate at planting time. Use a high phosphorus starter solution in cold, wet weather.
3. Transplants set before May 1 are most prone to buttoning or bolting. Plant the early crop in well-drained fields. Block or plug transplants are recommended for the early crop as they establish faster.
4. In hot, dry weather irrigate both before and after transplanting.

Cabbage Splitting

Mature heads may split if rain or a heavy irrigation follows a prolonged dry spell. Splitting results when the outer frame of the head has difficulty in accommodating the rapid internal growth due to the increased moisture. Early varieties split if not harvested on time.

Control

Splitting may be reduced by “checking” the plant growth through deep cultivation between the rows to break some of the roots. Adequate soil moisture at all stages of the plant’s development will also help reduce splitting by maintaining steady growth.

Oedema

Under certain conditions, usually in the fall, cabbage left standing in the field following wet weather or over-irrigation will develop clusters of white to brown, puffy eruptions on the outer surface of leaves near the outside of the head. This is due to water being trapped between the leaves for a prolonged period of time. When severe, several outer leaves may have to be stripped off before the head is marketable. Feeding by thrips may aggravate the condition.

Control

Harvesting prior to the onset of fall rains and cool night temperatures which favour condensation of water vapour between the leaves will usually prevent this disorder. There are also differences in varietal susceptibility. Control of thrips may lessen but will not prevent oedema.