Thanks for the feedback. But please understand I still don't know what, precisely, you mean by water them well. As in how much -- 1 cup? 2 gallons? or what? As an example of how much detail a long-distance diagnosis requires, consider this when I tried to troubleshoot a veggie problem over the phone. The description sounded like a water shortage but the gardener said that "It can't be; I water daily." Then, after further questions from me, I learned it was with a drip system. Then, after still more questions, I found out the drip system was on for just 5 minutes a day. (Yikes!) The diagnosis: insufficient water in spite of daily watering. Okay, back to your dahlias. Here are some things to consider. Are these new or established plants? If new, the original rootball is most likely drying out,this because it is "missed" when you water. The water would have to be applied directly on top of the rootball, possibly drizzled rather than poured from a can or hose. If established, perhaps you aren't adding enough water. On the other hand, the roots might be drowning. Have you checked just how moist the soil is? (To tell the truth, I doubt they're drowning because the leaves don't show the correct symptoms.) How hot and/or dry has it been recently? Also currently is? Do you have burrowing critters? Moles can tunnel under plants, thereby redirecting water away from roots. And gophers just plain eat roots/plants I suggest a water shortage from whatever cause because of the dried leaf edges and tips. You will need to be our on-site detective. Check the soil moisture content. Perhaps even sacrifice a plant by digging it up so that you can see what's going on in the rootball. Let us know what you find.

Did you fertilize with anything that might be burning your leaves? When I had a couple container type dahlias, I recall that they were the first to go as far as blooming went. Those are the only things I can think of for what you describe. I'd just take the brown leaves off, they're not coming back to green, I don't think. Maybe your plant is taking a breather and will have a second spurt?

Hi jordanmichelle, I agree that the photos look like a bad case of Powdery Mildew. " I'm really confused how it got this powdery mildew. I water only at the base and live in a very hot and dry climate. We're experiencing a drought and it's been in at least the 90s throughout the night the past month and well over 100 during the day. " Whenever the subject of Powdery Mildew comes up, someone usually suggests wet foliage as a possibly causative factor. It is a popular misconception that water on foliage promotes Powdery Mildew. The truth is the opposite -- water on foliage can actually fight Powdery Mildew. Powdery Mildew thrives on dry foliage, and when it cools at night it gets the cool dry conditions that favor it. By watering only at the base you were following the advice of those who identify wet foliage as a cause of PM. Unfortunately, they are wrong. Some foliage diseases are favored by wet foliage, but Powdery Mildew is not one of them. ZM

Are you seeing any positive effect after spraying the Neem oil? This is a serious infection! I can see the webbing on the first image, now that it was pointed out. I've never seen it this bad. Here's a post from a dude on a 'roll Em up' site about growing pot, (amazing what dahlia growing tips you can get on those sites!) which has very interesting commentary on fighting mites with Neem Oil: "so here are a couple things about neem oil... i use it and swear by it so ill give you my personal experiences with it...first i've used neem oil under HO satellite IV floros on a 24/0 crop with NO problems.. i didnt have any burn from the water or the oil magnifying light... no ill side affects at all.. so if you are using floros i would venture to say you'll be fine spraying during a 24/0 light schedule... just move the lights when you spray so you dont spray the lights themselves... make sure you get under the leaves and the "inside" of the plant just as well as the topside of the leafs and "outside" of the plant... like was said those little bastards live under the leaves so take time to spray well... secondly neem oil can be root fed to your plants as well.. during the entire time i have an infestation i feed neem to my plants... ill explain what neem oil does and why root feeding is good in the next paragraph.. but i feed each plant about 6 ml per gallon of water every other feed.. you can just incorporate the neem into your regular feeding schedule... only do this if its soil though... i wouldnt recommend it for hydro... here is how neem oil works.. neem oil is NOT a spot killer.. you wont spray your plants today and be gone of mite tomorrow... expect about a 2 week battle... neem oil works a couple ways.. first if you can spray the eggs well it covers them and suffocates them... no more eggs.. when the adults eat the neem oil it messes with their hormones... it makes it so they cant reproduce and lay eggs.. immature pests that eat the neem oil dont reach adult hood and are never able to reproduce... thats why spraying the plant well is so important.. you want to make sure the mites have no choice BUT to eat the neem oil... root feeding work very similar in that the pests hormones get ***** up when they suck the juices from your plant, but it also deters them from sucking on your plant because the neem oil tastes horrible... it also contains some trace minerals so its actually good to feed your plants,, i personally will root feed my plants every other time during and infestation, and spray them every 2-3 days.. the spray i use is 3ml neem oil per 1L of water with a few drops of biodegradable liquid dish soap... usually following this over a 2 week period.. then just go down to spraying once a week as a precaution... ill do this up to the 4th weeks of flowering.. havent ran into mold problems yet, or had neem flavored buds, or any other side affects due to the neem oil... its always worked for me.. like i said.. it just takes about a week before you see progress, 2 weeks before the infestation is gone... but its a natural way to get rid of them... if you want an immediate solution get some NO PEST STRIPS from walmart, lowes, home depot, ect.. they will work in a few hours and kill both mites and eggs... but it is a chemical strip (not a spray)... personally i dont want to think that what im inhaling was treated with a chemical... NO PEST strips work tho.. just make sure you arent in the area because they arent anything you want to breath in... also AVID and FLORAMITE are instant working sprays, but again they are chemical... chemical = instant, but it is a chemical you are using on your plant... natural = longer time fighting the pests, but its not chemical.. just depends on you... also.. a couple smaller ways of helping slow down their life cycle and battle them is; 1) keep humidity up... they hate humidity... spraying with cold water will help by raising the humidity, spraying them off the leaf surface, and they dont like cold.. which brings me to number two.. 2) drop the temps to between 65 and 70 if you can... it can take 10 days for mites to reach maturity in cooler humid temps, but as little at 2 days in warmer less humid places... each female can lay 100 eggs a day... they are 75% females anyways... in the right climate they can very very very quickly run your garden over... so until you decide how you are gonna deal with them and they are dealt with making the enviroment as unhospitible to them as you can will help slow their growth..." simpsonsampson420, May 13, 2009