Phosphites have their role - but not in supplying P!
Phosphite salts are gaining popularity because of their fungicidal properties when sprayed onto plants. However, it is important to be aware that these products are not effective foliar phosphorus fertilizers as research work recently carried out at Yara´s Hanninghof Research Station has recently demonstrated.
Maize plants were sown and allowed to germinate and grow in an environment where the soil temperature was kept below 16 oC in order to limit phosphorus (P) availability in the soil.
Then the plants were sprayed at the 4-6 leaf stage with either potassium phosphite or one of Phosyn´s specifically formulated foliar "Phos" products.
The development of the plants was monitored and measurements of fresh and dry matter yield were recorded.
The graph on the right shows that the potassium phosphite treatment actually performed marginally worse than the untreated control because the plant was not able to make use of any of the applied phosphite.
Whereas the Phosyn "Phos" treatment gave an 8.3% increase in fresh yield and a 9.4% increase in dry matter compared
to the control showing
what an effective
source of phosphorus
these products are.
So if you have growers who are using phosphite fungicides it is important to explain to them that these products are not effective foliar nutrients.
It is still vital that correctly designed and formulated foliar nutritional products are used to ensure optimum crop performance and maximum returns on the investments.
Author: John Brooks, UK
Published: November 2005