Ah – I recognise the first of these troubles all too well! And clearly there’s no hiding behind a mystery virus - it’s all down to “bad cultivation”! To be fair I know that and have paid the price for the “found wantingness” of my watering regime – although given that it’s not all – in fact just a few varieties which suffer from it – I think the “design” of some tomatoes has a part to play. Plums in particular seem to be cursed by a leathery bottom! May be the connection wasn’t known when the book was published – but now the direct cause is known to be a lack of calcium. Calcium is transported around the plant by water: so insufficient water = insufficient calcium. And calcium is used in the building of cell walls – so the dark patch is a group of cells that lacked calcium with which to build those walls…However even blinding him with science – I still think Mr. C would let the words ” bad cultivation” be his last!
Blossom-End Rot
This tomato trouble is not due to any disease organism but is the result of bad cultivation. The symptoms are a well-defined circular patch of dark green at the bottom end of the fruit. This patch later turns dark brown or black and becomes flattened or leathery.
The primary cause is the inability of the plant to obtain sufficient supplies of water from the roots to maintain the expanding fruits. It is most often found on plants growing strongly with luxuriant soft foliage which may be the result of too much nitrogen in the soil. Foliage of this nature requires a lot of water to maintain it and if there is any shortage the fruits will be affected first. Faulty watering under glass so that the subsoil becomes dry, or a check to the water supply of an outdoor crop, perhaps during a drought, will invariably result in the appearance of this trouble.
Blotchy Ripening and “Green Back”
The names given to these two troubles are really self-explanatory. The first shows itself in the form of hard, dark-green patches on the fruit which only assume a yellow or orange colour when the rest of the fruit is ripe and a normal red. With “Green Back” the whole of the stalk end of the fruit fails to colour normally. Both troubles are primarily due to a shortage of potash in the soil and corrective measures should be taken by applying a dressing of sulphate of potash at the rate of 2oz. per sq. yard.
