Magnesium Deficiency
This problem spreads through handling, insects or soil rather than the weather, so there is no live forecast risk — focus on prevention below.
When it strikes
About
Magnesium deficiency is widespread on sandy, acidic and heavily potassium-fertilised soils, common in tomatoes, potatoes and roses, since magnesium is the central atom of chlorophyll.
Symptoms
Yellowing between the veins of older lower leaves while the veins stay green, often with reddish or purple tints and curling margins, progressing upward over time.
Organic Treatment
Apply Epsom salts (magnesium sulfate) as a foliar spray or soil drench for fast relief, and add dolomitic lime to acidic soils to correct it long-term.
Chemical Treatment
Magnesium sulfate soil application; dolomitic limestone where pH also needs raising.
Prevention
Maintain balanced fertility, avoid excessive potassium, lime acidic soils with dolomite, and build organic matter.