The Sunday Mail
Word from the market with AMA
The 2021/2022 farming season has so far taken off on a very bright note for farmers in Zimbabwe. As we progress into the season, farmers are still looking at planting crops such as common bean which is an important crop for Zimbabwean farmers.
Bean growers must have good quality bean seed that is free from diseases and can germinate into a viable crop stand. The presence of seed borne diseases namely bacteria, viruses and fungi can affect the quality of bean seed and compromise anticipated crop yields.
Farmers in Zimbabwe buy and use certified bean seeds and it is generally recognised that good quality certified seeds achieve the required germination. However, it is not all bean growers who use certified seeds stocks.
There are cases where communal area farmers and farmers in irrigation schemes use farm retained bean seeds and it is important that such seed is free from seed borne diseases. The retention of farm saved bean seeds also acts as a repository for crop diversity that would otherwise go extinct without being grown by farmers.
Seed borne diseases of
common bean
For common bean, the major seed borne diseases that can cause challenges at germination include bacterial infection (Photo A), and charcoal rot infection (Photo B). Other important seed borne disease include angular leaf spot and bean common mosaic virus.
It is important to note that charcoal rot will cause each infected seed to completely fail to germinate as shown in photo B.
Advice for farmers
who retain seed
Farmers who retain bean seeds are advised to carefully select seeds through visual inspection.
Dark stained seeds usually carry diseases and research has shown that removing dark stained seeds serves to remove the bulk of diseased and unviable seeds from a seed lot.
This in turn improves the germination potential of the seed lot.
There is also the use of seed treatments with active ingredients that are available on the market.
Chemical seed treatment reduces surface contamination by some diseases.
However, research has shown that chemical seed treatment does not resuscitate seeds where the embryo is no longer viable. In other words, seed treatment only works on live seeds and cannot resuscitate dead seeds.
Other considerations
on bean seed stocks
Traders and agro-dealers who handle common bean seed are advised to
ensure that seed is stored at an ambient temperature that does not lead to loss of viability.
Bean seed stocks should preferably be stored in a well ventilated storeroom that is cool and not excessively humid. Storage of seed under very humid conditions can render even certified seed stocks to lose viability and can lead to infection by dry rot storage fungi.
Farmers must take full advantage of the current good season by planting common bean as the season progresses.
Word from the market is a column produced by the Agricultural Marketing Authority (AMA). This article was written by Dr Walter Masakure Manyangarirwa, Head of Department of Agricultural Sciences at Africa University. Feedback: [email protected]; [email protected]; [email protected]
