Can anyone tell me what is doing this to my chrysanthemums? This leaf is from one variety of chrysanthemums but no other varieties outside this one has this problem. Is this caused by a pest that can be treated or is it a disease that needs to be burnt in order to be rid of? All my chrysanthemums come from cuttings from the previous years plants. I appreciate any feedback...Thanks in advance, Cheers
This looks like "Black Spot" but there are different causal agents for different plants. The best course here would be to see if you can track down "Black Spot" on Chrysanthemums either here on DG or surfing elsewhere. Sorry I can't be of more help.
Brian
Hello chrysies. I am no expert on chrysanthemums either but have had them for many years.
I would take any affected plants and immediately cut them back to the ground. Isolate them and see if any new growth is affected . I would spray all the others with a good systemic spray in case you have mites and I have found that a spray of powdered milk and water will help any black spot, mildew or other fungal problems.
Do you grow the plants in the open ?
I keep mine in pots in full sun . They like lots of air around , so don't have them close together.
I have found that using a stake early and tying to this as they grow, keeps them upright and clear of each other. Chryssies do have a tendency to flop all over the place if left.
I tip prune mine during the year from when they are about 8" tall
They like to be fed and I use a good fertiliser such as Thrive alternated with Seasol and once every 3 - 4 weeks, a feed of either The Recipe ( from the brug forum ) or a mix of brown sugar and water
If you grow yours in the ground, it may help to keep the bottom 6" of the stalks free from leaves to encourage good air flow.
Jean.
Hi Brian and Jean, thanks for both of your comments. A few answers to your questions...they are grown in pots in my shade/poly house...in the wet times they are covered with plastic to protect the blooms, of which are only just starting to appear, but when it is dry, the plastic is taken off to allow ater in and air flow. They arent too close together, they barely touch each other. They are always staked and trimmed and fed at the right times. The bottom lease are always trimmed from the stem also. I usually use seasol and powerfeed when the time is right. As I have said in the two posts that I put in, the curling leaves are from one variety and the spotted leaves are from another variety. All the different varieties are mixed up together but it's the same two varieties affected throughout the poly/shade house. Where the house is, they get a LOT of shade, which is great for the summer but not so good when the weather is damp...but I would have thought that ALL the plants would have been affected if it was a damping off problem...unless those two varieties are more suseptiple to disease. I am going to try a milk treatment that I have available to use for mites and blackspot, to see if there is any improvement, problem is, that I can't use too much now that they are starting to bloom, as any sprays affect the petals and makes them look ratty. I try to have the pests under control. before the blooms are out...Thank you both for your comments, and I look forward to any more...cheers GG
Hello, I just checked my old Tafe notes, and I deduce it is fungal. Reasons? Black/brown spots, rounded, straddle the viens and produces a target spot (yellow around the edges) Fungi are spread by spores.
http://www.ipmcenters.org/CropProfiles/docs/OHChrysanthemums.pdf go to page 12
Sue
