Section 1: The Groundnut Plant
Discussion of pH and lime – Page 16
A soil survey of 850 maize, groundnut, and soybean fields in five selected districts (Lilongwe, Salima, Ntchisi,
Kasungu, and Mzimba) found a range of pH, but the average was approximately 5.2 – lower than optimal. To
maximize nitrogen fixation, growers may apply inoculants, but these perform poorly when the soil has a low pH
and are most effective when the pH is close to 6.0. The fact that so many fields are below optimal levels is an area
of concern for groundnut growers and yields will remain suppressed until soil conditions are addressed.
Use of Inputs – Page 18
Recent trials conducted in Malawi indicate a benefit from the use of inoculants and increased biological nitrogen
fixation and yield, but this was not observed to be consistent across locations nor across all varieties. This same
inconsistency is seen in many countries where inoculants are used, but data trends indicate value in using them at
plant particularly if soil pH is higher (above 5.5).
Under low soil pH conditions, which is a common situation in Malawi, the application of gypsum may actually
reduce yield.
Studies conducted in the 2020-2021 growing season on the impact of boron and calcium applications
demonstrated a strong positive impact on yield across two locations, both Chitala and CG9 varieties, and when
applied at different dates in fields with soil pH near 6.0.
Photos of diseases – Page 25
This version of the guide contains new photos to illustrate the symptoms of the most common groundnut diseases.
Early leaf spot (ELS) and late leaf spot (LLS) are two foliar diseases caused by fungus, while rust is another fungal
disease that sometimes occurs along with leaf spots. Another disease, crown rot, can kill seedlings. The biggest
threat to groundnut yields is groundnut rosette, a complex of viruses that is spread by aphids. Updated images in
the guide show the two main types of rosette, chlorotic rosette which turns young leaves yellow and green rosette
which can be identified by severely stunted plants.
Evaluating practices – Page 48
A new section explains the basic method for testing best practices on an individual’s field, since each plot is
different, and research conducted under different conditions or in another area and may not apply in a particular
farmer’s field. Simple comparisons can help a farmer to understand the value and the risk of practices and whether
inoculant, fungicide or herbicide contribute to yield and profitability.
Graphic - Addendum
Optimizing Groundnut Yield and Minimizing Aflatoxin is a two-page handout, prepared for farmers to see the
relationship of pod maturity, yield, and aflatoxin contamination.