I wouldn't assume that the browning leaves are a result of the scale infestation, either.. Scale on houseplants can be controlled by the use of a horticultural oil spray. You can find oils at any garden center.....read, understand, and follow the directions. You can apply hort. oils with a simple plant sprayer. As to the dying leaves and stems, I'd look very carefully at your watering practices and the quality of the potting medium for answers.

You have some very healthy plants with the variegation or silver-veining characteristic of several squash species. Now that you know it's not a fungus, isn't it pretty? Every time I've seen fungal disease on cucurbit leaves, there's: 1) a dust that brushes off and 2) wilting and later, dead or browning leaves. These are clean, turgid and healthy.

if you havent already.. separate the plants as best you can ... read a bunch of these: https://duckduckgo.com/?q=potassium+bicarbonate+homemade+fungicide&t=ffcm&ia=web by the time you read thru a couple.. you ought to get the jist ... do not spray in sun ... or on hot days ... etc .. all the general rules .. adding actual leaf damage/burn to your problems wont accomplish much .... and here is a truism.. many say.. you arent a green thumb.. until you have killed every plant.. 3 times ... so if you lose ... so be it ... try again.. and trust me.. you will have learned something for the next time you try ... welcome to the forums... plz come back often ... ken ps: it is usually helpful to include your location.. big city name ... in this case.. im not sure if you are still holding these indoors ... as i would be here in MI ... or if they are already outside ... and if they are outside .. did you harden them off before they went outdoors ... can we rule out leaf damage from shipping.. transplanting.. sunburn ....etc ... there are many things that should be ruled out.. before we start spraying them ... a pic might help ....

I sometimes trim all the leaves off (many) different plants if they are bad looking. The plant has to put out new growth if it wants to live. The reason most plants are easy (semi-easy) to propagate is their ability to put out new growth if they get broken, eaten, mowed, or dumped on. Indoors for winter, I really cut back on watering which seems to help a lot on mildew outbreaks. Being in a basement is conducive for mildew (damp, cool) but most come through winter okay. More light would help but my spaces are crowded so most of the canes go on the floor near a stand with the lights. Spraying with a fungicide will help tremendously but I really hate to spray if I don't have to. The mildew got so bad on my maculata (hybrids) that I had to do something as a lot of leaves had already fallen and I picked the rest of them off if they even had a smidgen of mildew on them. PS: I find the maculata hybrids to be more susceptible to mildew than other types of canes. This parviflora had so many damaged leaves that I cut/pinched most off May 23rd after putting it in a larger pot (I want to get a big plant again) This is what it looked like July 18th with a few pinholes either from insects or falling debris/maybe hard rain. This is what it looked like when I had it in a huge pot with other canes back in October, 2015.