Pepper disorders and diseases

Rough handling can lead to damage of the skin, at any stage of the supply chain. For example, the effect of harvesting in bags can manifest itself in bruises and injuries at a later stage. Bruising can also occur due to too tight packaging, broken field crates or over-filled crates that causes pressure on the peppers. Bruises are usually soft with discoloration of the underlying flesh. These mechanical damages not only make the fruit unattractive but often also lead to secondary rot development. Sun damage symptoms are a lighter, sometimes white, colour of the pepper skin.

Peppers should not be stored below 7 °C as they are sensitive to too low temperatures. Symptoms of chilling injury include pitting or sunken spots on the skin, skin discolourations, pulp water infiltration, off-flavor, shrivelling and increased susceptibility to decay. This disorder is caused by several days of storage below the minimum temperature. Damage depends further on the duration and of the temperature. The longer the period at low temperature and the lower the temperature, the greater the damage. Symptoms appear especially after transfer to higher temperatures.

Peppers can show signs of corking on the skin. This is a pre-harvest issue that happens when there is a disbalance of the internal and external growth of the pepper, where the internal part of the peppers grows faster, producing vertical skin marks to recover the difference in growth. Peppers showing these traits might be declassified but are still edible.

Peppers have high water content. Some of this water is lost by transpiration. However, water loss through punctures or otherwise damaged skin can be significant. Some shrivelling of the skin can then occur. Desiccation can also lead to loss of glossiness. The risk of shrivelling symptoms increases with a combination of low relative humidity and higher temperature increasing the vapour pressure difference.

One of the most common mould is the grey mould or Botrytis. Unfortunately, Botrytis can continue to develop at the storage temperature of the peppers. Therefore, the prevention of Botrytis remains very important by avoiding mechanical injuries. Long periods of high humidity or condensation can stimulate the growth of stem-scar moulds. Especially when the stem is not nicely cut at its natural breaking knot. These moulds can be of a light type, and disappear, for example, after opening the (foil) packaging and exposure to the drier outside air. It does not necessary lead to breakdown of fruit tissue. But if the mould causes tissue to decay, this of course has serious consequences for the marketability of the pepper.

Several types of pathological diseases can occur, such as Alternaria, Erwinia, Pseudomonas, Bacillus, Xanthomonas, and Cytophaga. For example, Alternaria manifests in wounds and bruises. Bacterial rot can be caused by, for example, species of Erwinia, which gain access through insect punctures or other skin injuries. In addition to damage, rot is often also linked to senescence. The development of rot after harvest can often be controlled by quickly cooling and preventing bruising and injuries.

Overripe fruit can easily deteriorate, it is a consequence of aging. Surface breakdown, softening and off-flavours are part of the deterioration. This last stage of the fruit is called senescence. Senescence is enhanced by higher temperatures. The peppers with senescence symptoms may have been stored under suboptimal conditions such as too high temperature or were simply stored or in transport for too long.

Peppers can show silver-like skin made by previous thrips infection. Although perfectly edible, thrips leaves traces on the skin will declassify the peppers.