Dahlia problems

I started dahlia bishops children indoors in January. They are currently outside in pots. Since the end of April till just recently south tx has been a bit wet and I've seen powdery mildew, snails, and worms. My Dahlia s are in pots. Leaves are a bit yellow and I see spots on the leaves. These plants have experienced mildew and snails. But they are still alive. How can i fix my blotchy leaf problem? If I can't is it too late to start over?

I started using daconil about two weeks ago and my problem doesn't seem any worse.

This message was edited Jun 9, 2015 8:20 PM

Dahlia's absolutely hate wet damp conditions, they do need a lot of watering when the weather is dry /hot etc, however because these ones you have are in pots, the soil is not being allowed to dry out properly and no air allowed into the soil to help prevent root rot or the tubers become soft and diseases can set in, they become a haven for worms, insects that eat rotting tubers etc.

The soft tissue of Dahlias is like a delicacy to snails and slugs and more prolific because all the wet weather you are experiencing so you need to take some form of defence against these beasts, they can devour the whole row of Dahlias in a single night. You need to try and control these pests by either going out after sundown and try pick them off the plants, search all over the plants, under the leaves etc as they like to hide away from predators like birds etc.

Other ways is to try place half empty skins around the pots as the slugs / snails find these areas a hiding place and you collect the skins and snails in early morning, remove the slugs and replace the grapefruit skins for trapping another load next morning.

There are also pellets you can buy at the garden store, you sprinkle a few around the stems /Pots etc and these pellets kill the snails / slugs etc by drying the slime these creatures need to get around and keep themselves moist. Make sure IF you buy this type of slug killer, you look for the type that will not harm / kill any other animals,

It may take a couple of years before you get flowering size tubers, the Dahlia's are slow to get going from small cuttings taken from the parent tubers, but once they build up the size of tuber, about 2 years /seasons, they will begin to produce flowering buds.
The yellowing of the foliage is usually a sign that there is a deficiency in the soil so make sure the soil in the pot is of good quality, dont over water, give a half doze liqid feed at one of the watering's but only WHEN the water is required. dont start over feeding as that is even worse than NOT feeding.
Hope this helps you out a bit and all picks up and you get good results.
Kindest Regards.
WeeNel.

The fact that the issue hasn't progressed since you started using daconil is great. It won't stop the damage that has already been done but it will stop it from spreading.

Ditto WeeNel:
Better drainage, perhaps lift the pots up a bit onto some kind of grid that would keep them off the ground so they can drain better.

Hand picking pests like snails and slugs can help. Be very careful with bait, the baits are toxic to animals and the pellets are attracive to dogs. I have used Deadline successfully- really kills a lot of snails, and SEEMS safe around dogs, but I won't use it in the parts of the garden where my dogs can get to it. It is a liquid that you apply in drops in scattered locations. The drops could be hidden behind or under things where the dogs cannot reach, but snails and slugs can crawl into.

Good air circulation is the key to controlling most fungi. Sprays to protect the new leaves are important, too. Re-apply per label directions. Most of these controls work by preventing the fungi from entering the leaf, so they need to be on the plant before the fungi spread.

I did think that maybe since its been real wet the last couple months and still more rain on the rain i think this week. All the essential nutrients that were in my soil are all washed out. started using miracle gro all purpose food last week. Is that a good brand? It says to reapply every 7 days i think. Its at home and im at work so im not certain.

I do go out at night and early in the morning to pick out any pests. I used a cheap beer in a shallow dish and the snails loved it. I most just pick them off now. they really loved thos dahlia leave and the leaves to my daisies. those barely made it out alive as well.

Dont over feed especially with that brand, people think the more feed they pour into the plants, the healthier they will become, not so, over feeding can make plants weak, cut off growing as they cant cope with the heavy feeding, so be very careful.
I would rather you improve the light, the drier soil conditions required, and as Dahlia tubers grow, maybe you require a slightly larger pot with fresh compost, dont bury the tubers deep, they just need to be only just under the soil in no more, too deep and the tubers can rot, get eaten with insects that thrive on rotting matter under the soil.
Hope this helps you out a little more to get the growing conditions correct and the plants thrive without too much more trouble.
Kindest Regards.
WeeNel.

There are very basically 2 types of fertilizer:
Slow release- apply just a few times in a season, or maybe just when you dig the bed between plantings. Mostly these are 'organic' materials like blood meal, bone meal, manures, and certain minerals. Or in-organic materials coated to last several months. Osmocote is an example.
Generally this type of fertilizer will not burn the plants, but also will not give fast results. These sorts of fertilizers are very good for the soil microorganisms, and will improve the soil over the years. The slow release does not promote excessively fast growth in the plant.

Fast release- apply often, such as weekly, or with every watering or similar. These are often salts of the elements that plants need. Miracle Grow is an example. I feel this sort of fertilizer produces as sort of 'feast and famine' sort of condition in the soil. There is a lot of it when you apply it, but since it is water soluble any the plant does not take in is washed into the water table, or elsewhere, lost to the plant. Then the soil has little fertilizer until the next time you apply it. These fertilizers do not have the materials that help the soil microorganisms. I prefer to save these for foliar feeding, or when a plant can really make use of the fast release.
They can encourage such a fast, lush growth that it is too succulent and insects and diseases can more easily attack the plant.