Onion storage is an integral part of onion production in Zimbabwe. Onions are an easy crop to produce in this country but are much more difficult to successfully market. This is because two to four months can elapse after reaping before the market stabilises and prices start to rise. Onions are difficult to sell when first reaped but a few months later Zimbabwe has to import them from RSA because the onion crop can perish in the store.
Onion-rotting in storage is mainly due to fungi, although bacteria can also play a part. Many of the fungal species involved in rotting the crop in storage can be carried into the storage bin from the field.
Of late more problems are being experienced with onion storage than previously. This is because many growers are not sticking to a four-year rotation to help reduce harmful soil-borne micro-organisms.
A one-year rotation will lead to a build-up of harmful fungi in the soil.
Where a grower has experienced problems with onion storage he should use a fungicide from +/- four weeks before pulling.
Some of the fungi that can affect onion storage include Fusarium, White rot, and Neck rot.
Onion shelf life can be prolonged by three to four months if stored in bins and forced air is used to control the relative humidity in the bin.
The reaping procedure for onions recommended by Charter Seeds and the temperatures and humidity required to prolong the shelf life of the vegetable in bins will be given to Charter Seeds customers on request.