Hi, Well sadly there are a number of squash ailments with spotted leaves as a symptom. Can you describe the white spots? Are the leaves distorted, too? Are they round or angular? My first guess is that this is either a Downey or Powdery mildew which is common during wet, humid periods. Always avoid overhead watering of this crop and destroy all dead or dying foliage You can prevent the outbreak from getting worse by using a vegetable garden fungicide, but I recommend leaving it alone and starting over next year. Also, be aware that there are mildew resistant varieties. When you buy seeds read the seed pack to see if the variety you are purchasing is disease-resistant. Again, without a more detailed description I can't be sure what's going on, but if you've had a lot of wet weather one of these mildews could be the problem. Just don't let the old, diseased plants remain in your garden over winter.