For my first blog, I would like to discuss low fertility in plant analysis that is not caused by deficient soil nutrients. We have noticed in the past that low petiole phosphate may not respond to side dress or water run P applications. This has been caused by soil borne diseases and this year in Sugarbeets, by nematodes.
We have a field in the Imperial Valley that had adequate levels of P applied preplant. It was grid soil sampled and had GPS precision applied 11-52-0 prior to planting. The soil is sandy loam texture with a 1/4 mile length of run. About 2 months after establishment, the headlands began to show low petiole P (less that 1000 ppm PO4-P). We applied sufficient 10-34-0 as a water run to correct the deficiency. The petiole p did not respond in the follow up petiole samples. Soils were sampled in good and poor areas, no differences were found in extractable P (Olsen Method) and levels were adequate for good beet production.
Last week the same areas were sampled for Nematodes. Parasitic nematodes found included longidorus, stunt, and spiral.
In conclusion, the cause of the apparent low petiole phosphate was not nutrition based, it was a problem with a damaged transport system within the plant itself.