That is powdery mildew on your squash plants. If the soil is bone dry while the pepper plant is wilting yes it is under-watering. But the same wilting affect can be the result of other problems including over-watering.

Debbiecz, it is typically best to start a new thread wih your issue to get more eyes on your issue and to reduce confusuion since you are the third different person to have an issue arise on this thread. Go to the top of the page and click the little gray oval with the word perennials in it or just click the link. https://www.gardenweb.com/discussions/peren Then where is stays “start a discussion”. You can start a new thread devoted just to your garden. Be sure to add photos of your particular garden and info about your general location and soil. What plants are you putting into the bed that haven’t been happy? Generally a failure to thrive is either due to soil, watering, or a plant choice that isn’t appropriate for your particular setting. Since this is a raised bed and plants have done fine here previously, your problem may be the soil used to fill the beds originally if it wasn’t native soil. Often bagged “soils” will break down because they are high in peat, and over several seasons will become extra fine textured and dense, reducing the movement of needed oxygen and water to and from the roots. Try digging a hole several inches down -what does it feel like? Wet, moist, dry? Loose and crumbly or dense? If you put a cup of the soil in a quart jar with water and shake it up, how long does it take to sink, and if left to completely settle, how thick are the layers and do they look like soil particles or organic material? I could be completely off base, but I am guessing based on the little bit of info you gave us as to what the problem might be.

I'm going to assume it is a fungal disease. Your watering is wrong enough to possibly get a root rot going. Would you mind posting a picture? The best garden pictures are taken on an overcast day to reduce the contrast between brights and shadows. For this the distance should be about 6 inches away. I have had a similar disease issue in my St Aug where it returned time after time, but mine was a surface disease and not affecting the roots. Mine did not go away until I treated it with corn meal - yes, the same stuff you eat. Apply at 20 pounds per 1,000 square feet over the entire yard. You can buy it in 50-pound bags at a feed store. Call first to see if they have it. Ask for the price. It should be well under $15 and more like $5. If the price is above $20 then it's not corn meal but corn gluten meal. That won't work. You want ordinary corn meal. Cracked corn will work, but don't use whole corn. Whole corn will turn your yard into a corn field (easily mowed down). Corn meal works biologically and not chemically. The corn decomposes with bacteria and fungi already living in the soil. One of the fungi that seems to accumulate especially well on corn is Trichoderma (try ko DER mah or trick oh DER ma). This is a predatory fungus that feeds on the disease causing fungus. Give it three full weeks to show improvement. If it seems like it is working, but you want to really hammer it home, reapply. If you have already used a chemical fungicide in the past few weeks, then corn meal won't work. Why? Because the Trichoderma has been killed off by the fungicide. In the future you should change your watering. I realize 99% of all Floridians water daily, but they are all wrong. All of them including the sprinkler guys who set everyone up. Here's more about watering. Watering: Deep and infrequent is the mantra for watering. This is for all turf grass all over the place. Deep means 1 inch all at one time. Put some cat food or tuna cans around the yard, and time how long it takes your sprinkler(s) to fill all the cans. Memorize that time. That will be the time you water from now on. My hose, sprinkler and water pressure takes 8 full hours to fill the cans. Your time will likely be less. I like gentle watering. As for watering frequency, that depends on the daytime air temperature. With temps in the 90s, deep water once per week. With temps in the 80s, deep water once every 2 weeks. With temps in the 70s, deep water once every 3 weeks. With temps below 70, deep water once a month. Note that you have to keep up with quickly changing temps in the spring and fall. This deep and infrequent schedule works in Phoenix and in Vermont, so it should work for you. The reason for deep and infrequent is to grow deeper, more drought resistant roots and to allow the soil to dry completely at the surface for several days before watering again. If it rains, reset your calendar to account for the rainfall.

Hi, Ellie. Whether or not the symptoms are fungal in nature, it's a pretty good bet that they're at least indirectly related to the limitations/stress imposed by over-watering. A plant's natural defenses are a byproduct of it's metabolic rate. Since over-watering causes a limited oxygen supply, which in turn causes depressed root function and a 'back-slid' plant, we should have either an appropriate medium/soil in place (one that allows us to water to beyond the point of soil saturation w/o having to worry the soil will remain waterlogged for extended periods and wreak havoc on the root system), or work-arounds that effectively trump the soil's ability to hold excess water ..... more about that if you have interest. An appropriate medium makes a very distinct difference in our ability to provide the cultural conditions that allow the plant to realize as much of the genetic potential given the plant by Mother Nature as possible. We can be sure she will always side with any flaws hidden in our habits. The dots look very much like caterpillar excrement - not a diagnosis - just an observation. Check to see if the dots are stuck to the plant but come off reasonably clean if rubbed with a toothpick, or, if you crush the dots with a toothpick, is there a viscous liquid that oozes our from under the 'shell'? If 'yes' to either, suspect a scale infestation to be causal. If scraped with a toothpick, does it leave a dark powdery residue on the leaf? If yes, possibly a fungal or fungal rust issue. Al