Leaf Tip Death with Red Margin Typical Salt Damage

Q. Any idea what is causing this discoloration on the hawthorn leaves?

A. This kind of discoloration with the red margin is typical of salt damage/drought. Salt damage can be from a lack of water. Why? Because as the water in the soil becomes more scarce the remaining salts in the soil/water solution becomes more concentrated resulting in a higher concentration of soil salts than the plant can handle.

When the soil is wet this salt level is less damaging. When water become scarce then these salts are more concentrated causing damage from salinity. One strategy for minimizing salt damage to plants is to water more often with smaller amounts of water so that the concentration of salts never gets to be damaging.

In this case this plant is in rock mulch. Indian hawthorn is not found in soils with much salt in them and it is not originally from the desert. So putting it in rock mulch is a bit of a gamble in the long term. It will not handle salty soils or drought very well.

Compost is full of good salts. These salts are "fertilizer" salts and not bad salts full of sodium, chlorides and the like. This is why Viragrow encourages you to plant in WET soils, not dry soils. If you plant in dry soils you run the risk of salt damage to those plants that are sensitive to salts and salinity.

The only other thing you can do besides adding water is to add a soil penetrant safe for plants such as PenMax which sells for $29.99 per quart and $89,99 per gallon. It helps water move through the soil if that is a problem. Otherwise, don't use anything else. Gypsum will not help unless there is a reason for applying gypsum. Use 2 oz of PenMax applied to 100 square feet. Usually this is mixed in 1 gallon of water in a spray application. The quart container has a hose end applicator included for this purpose.

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