Nice to hear from you. I like to use the last fully developed leaf for all forms of sap testing. These leaves, rolled into a ball until the juice stains your hand, prior to placement in the bowl of the garlic crusher, offer the best indication of gains from foliar applications. They are definitely better than petioles for this purpose. Warm regards, Graeme

Nice to hear from you. The use of gypsum and phosphonic acid for control of sclerotinia is a little different in that it is not really about increased cell strength. The phosphonic acid is actually mistaken for phosphorous by the pathogen and this disrupts the metabolism of the disease organism. Gypsum seems to be used as a synergist to increase the disease management of several control chemicals.

By contrast, soluble silica is actually increasing the barrier potential of the cell wall while simultaneously boosting the immune system (defense mechanisms) of the plant.

There may well be a link in that the excess nitrates probably induced the disease in the first place.

i agree that there is huge, unrecognised potential in lifting sap pH as a proactive disease management tool. This may involve calcium (which is locked up by excess nitrates) but can also involve increasing potassium because high nitrates actually impact potassium uptake more than calcium.

The problem here is that standard tissue testing does not necessarily detect this potassium deficit. Potassium is so mobile that it will move from lower leaves to the upper leaves and fruit where it is required. The sample is taken from upper leaves to where the mineral has moved so the shortage is not immediately detected. The sap pH drops in the lower leaves and this can be why the disease begins in these leaves.

The trick is to use an Horiba Potassium meter for field monitoring. The K levels for the top leaf should be within 10% of the levels for the lower leaves. This is the way to pick up a K deficiency the moment it begins and it can serve as a great proactive management tool.

I feel that a combination of sap pH monitoring, the use of calcium, boron and silica (preferably together) and the introduction of inexpensive, brewed, bio control organisms (with bio stimulants), is the secret to sustainable pest management and I just wish more growers would experiment to discover this potential for themselves.

I trust this has been of help to you.

Warm regards, Graeme Sait

Nitrogen is the most mismanaged of all minerals. It is certainly an important mineral but the big response sponsors overuse and then the problems begin. Nitrates are the issue as there are over 200 published papers linking nitrates to cancer. Excess nitrates reduce the capacity of blood to carry oxygen. Professor Otto Warburg won his Nobel Prize for for discovering that anaerobism is the root cause of cancer. It is good to avoid hydroponic produce, in this context, as this food is only grown with nitrates.(calcium nitrate and potassium nitrate). That is why the brix levels in this produce are so absurdly low. Nitrates are always taken into the plant with water and there is an inevitable nutrient dilution factor. Brix is essentilly a measure of nutrient density.

The nitroge /potassium ratio in plant tissue must be lifted to 1:1 if you are running high nitrates. In this manner you have really created a rod for your own back if you have overdone the nitrates. Not only have you spent more than you had to on nitrogen but you now need more potassium, the most expensive of all minerals.

Kind Regards, Graeme Sait

Great strategy for managing the current Pythium ‘scare’ in the Ginger industry. Thank you.