I have some ‘Pansy’ sweet pea plants purchased as plugs from Jersey Plants Direct. They have developed black spots on the leaves, some leaves have withered and died. I contacted Jersey Plants, whose advice was the wet weather and to remove the affected leaves. I am not convinced though. Any ideas on my problem?
Certified GKH Gardening Expert
It does sound like a mold or fungus of some kind, which is generally lumped under the heading of "black spot". It is similar to the black spot that is common on roses. High moisture does aggravate the issue.
That being said, plucking the leaves is helpful to keep it from spreading, but you can also use a baking soda solution of 1 tsp baking soda to 1 qrt water. Spray this on the plant to help kill the black spot. Also, make sure to water the plants from below near the soil. This will help stop it too.
There is a fungus called Black Spot that form on roses foliage that will totally defoliate a rosebush if allowed to take control. It loves the wet or humid weather as alot of funguses do. I would recommend spraying the plants with a fungicide for the control of Black Spot fungus. One such fungicide that is on the market that is more earth friendly is called Green Cure. I use it on my roses and veggie plants. It controls the black spot fungus and also powdery mildew. Pulling off the leaves may help in light cases but it is hard to get all of the fungus that way without defoliating the plants yourself and that will likely kill the plant. Keep in mind that once black spot has made its mark the spots do not go away until new leaves without the infection are generated. So you will still see black spots even when the fungus has been killed. The new foliage should be clean of them once the fungus is under control.