I have a pair of currant plants which I bought back in the spring which I've planted in pots. The leaves of both have had their leaves edges turn black and eventually fall off. One now has no leaves though it is showing signs of life still, while the other looks like its now doing the same thing. So my question is why? I live in the St. Louis, MO area and this has been an abnormally wet summer, so I'm not sure if that's at least part of the problem or maybe the whole problem, and I'm looking to try to still save them both yet if possible, if I can take some kind of corrective action(s) soon. I would appreciate anything you can suggest, for how to remedy this problem, with the currant plants.

Thanks for the help.

Henry Versemann

Answer #1 · Maple Tree's Answer · Hi Henry-Most likely this blackening and dropping of the leaves is caused by too much moisture. Several fungal infections including Anthracnose and leaf spot can infect these plants especially during warm humid conditions. These fungal diseases can start with small black spotting that will grow in size with the leaves turning more yellow through the center then dropping. Unfortunately we can't control the weather but keeping any overhead watering from contacting the leaves will help. Being planted in pots I'm assuming these plants are watered at the bottom which is best. Too wet a soil can also cause fungal diseases. These plants should always be planted in a well draining potting soil. Always use a quality potting soil or mix that in my opinion can only be found at the quality nurseries and garden centers. These quality soils will hold the proper amount of water and still drain well. The first growing season these plants need to kept moist but never too wet or dry. Browning of the leaf tips and margins and wilting would be an indication of too little water. It sounds as though these plants are getting too much water. Digging down 6 to 8 inches the soil should feel cool and moist but never wet or dry. Pots should always have drain holes in the bottom so that any excess water will drain from the soil. Too wet a soil can easily cause root rot and fungal disease. Inspect the top and underside of the leaves closely for any signs of small insects. Sap sucking insects such as aphids can attack currants. These insects suck the juices from the leaves and excrete a sticky shinny substance known as honeydew. Several species of fungi will grown on this honeydew covering the leaves with a dark grey or black layer of soot. This black colored mold doesn't infect the plant but the damage from the aphids and inadequate sunlight on the leaves will cause the leaves to die and prematurely drop. This aphid damage can also cause leaves to deform and curl up on the tips and margins. Checking the soil for too much moisture and leaves for any signs of insect damage may find the problem. Let me know if stems may be turning black and dying back. This type of damage is usually caused by more serious soil born infections which normally are not associated in most cases with a cleaner soil mix when planting in pots. With any of these problems heavily infected leaves should be removed and any leaves that have dropped picked up and disposed of. Splashing water from rain and sprinklers along with the wind can spread fungal spores to other plants. Neem oil is a safe natural fungicide/insecticide that can be used to treat both fungal and insect problems. Carefully read all product information before treating plants. For these products to be effective correct mixing and treatment schedules need to be followed.

I uploaded a few pictures below of fungal diseases and aphid damage to currant leaves. Let me know what you find when closely inspecting your plants.

John)