Picking and destroying affected leaves and avoiding splashing water from leaf to leaf or from soil to leaf can help to control these nematodes. Additionally, since these nematodes can exist for a short time as saprophytes in the soil or potting mix, repotting into fresh mix at the time of picking off the leaves can be very effective for control. Irregular or ring-like pale tan spots appear on the upper side of the leaves. These may vary greatly in size and severity since some cultivars are more sensitive than others. Injury occurs when water which is colder than the surface of the leaf is used for watering.
Symptoms are often more pronounced during the winter months.
This problem can be avoided by watering with tepid or room temperature water and by trying not to wet the foliage during watering. Soluble salt injury, excessive fertilization and accumulation of high levels of soluble salts in potting medium. Root injury caused by excessive levels of fertilizer in the potting mix results in a general decline or collapse of the plant. Symptoms are similar to those caused by root rot so soil analyses for soluble salt levels are often necessary for correct diagnosis. An indication of high soluble salts is the presence of white, crystalline deposits on the rim or outer surface of the pot or on the surface of the potting mix.