All 6 of my Costata Romanesco were totally destroyed by SVB. full of them. I did get a few nice squash and they cook up real nice. But CR is a c pepo and the SVB attacks. You can take care of powderly mildew with Serenade. I hear one aspirin per gallon water sprayed will also work. Hydrogen Peroxide will kill the spores. PM must be fought as a preventive. nothing will get rid of it once it gets deeply established into the leaves. butternut seems more resistant than pumpkins for example. By the time I see PM the season is pretty much over and I never bother with it. it might look terrible but it seems to NOT hurt the squash. about the time it overwhelms the vine the season is over. it usually hits the pumpkins more than anything else.

Homebody, your suspicion about bacterial wilt is probably correct, if you have cucumber beetle problems. You should also inspect the stem of any dying squash vines, to see if squash vine borers are responsible. If you find their larvae, or the holes left by them, then prevention next year is your best hope for success. And if your "white aphid looking creatures" look like this, then you should try to kill them before they reach adulthood. The symptoms of squash bug infestation can appear very much like bacterial wilt. Butternut squashes (Cucurbita moschata) are more resistant to beetles & borers than C. pepo (pumpkins & summer squashes) and C. maxima (buttercup, hubbard, banana squash). I quit growing zucchini for that reason, and now grow Tromboncino (a butternut relative) instead. It has few problems... but it does take up a bit of space, unless trellised. You can protect young squash plants with floating row cover, until they either blossom, or outgrow it. This gives the plants time to build up strength, so they have a fighting chance. For me, this prevents SVB, and by delaying the start of attack, reduces the population of cucumber beetles & squash bugs. I could not grow most winter squash successfully without the use of row covers - I highly recommend their use. The use of nylons or some other impenetrable wrap (around the base of the squash stem) can prevent the SVB moth from laying their eggs there. Also, try to grow squash varieties that root at the nodes; bury the stems early, to encourage early rooting... this will help the plants to survive, if SVB does kill the main stem. The last thing that you should do (after killing the squash bug nymphs) is to eliminate any pests that might otherwise over-winter. SVB pupae lay dormant underground, so a Fall tilling will kill many of them. Cleaning up any debris in or near the garden will help to reduce the population of squash bugs the following year.

Don't worry about the powdery mildew hurting your squashes. The winter squashes I have that have come from infected plants have lasted just as long in storage. Although, I would try to fight the powdery mildew because you really want to make sure they are ripe and given a change to grow all they will. Don't worry about any holes from your fingernail. It will not go deep enough to harm the fruit and should scar over quite fine and should not have an impact on storage.

I used Serenade and the Cornell formula this year on my zucchini and cucumbers and melons. Last year I fought SVB, PM, and some kind of bacterial thing. I did get a decent harvest, and my plants were troopers, but this year I am going to fight differently: 1) Row covers, row covers, row covers (for bugs which hurt the plant, making it susceptible to bacterial diseases and PM) 2) I will spray Serenade as a preventative instead of only as a treatment 3) I will have seedlings waiting in the wings 4) Last but certainly not least, I will continue to build soil health and mulch so that my plants are strong I found Serenade to be fairly effective, but once you have PM it is an uphill battle. Last year was my first year using it, and I was reluctant to use it unless I needed it, which may have been a big mistake. I am also considering kaolin clay.