I guess this is a multi part question on a)what happened to my vine b) and when to harvest pumpkin c)treating powdery mildew My pumpkin vine went from happy and healthy to collapsed in one in about 4 hrs. I have a feeling its bc I used my childrens leftover bubbles and put them on some leaves with powdery mildew but idk! . id been reading online using mild soap and figured bubbles should be mild enough...anyhow. All the leaves turned brown.. Ive enclosed photos of the vine healthy, collapsed and I think it's trying to revive. My other pumpkin vines are still currently happy and healthy
I am going to answer your pumpkin questions in the order you presented them.
A. What happened to my vine? I believe you answered your own question -- by using the bubbles liquid you inevitably killed your pumpkin plant.
B. When to harvest pumpkin[s]?
a. A pumpkin is ripe when its skin turns a deep, solid color (orange for most varieties).
b. When you thump the pumpkin with a finger, the rind will feel hard and it will sound hollow.
c. Press your nail into the pumpkin’s skin; if it resists puncture, it is ripe.
d. Harvest pumpkins on a dry day after the plants have died back and the skins are hard.
e. To harvest the pumpkin, cut the fruit off the vine carefully with a sharp knife or pruners; do not tear. Be sure not to cut too close to the pumpkin; a liberal amount of stem (3 to 4 inches) will increase the pumpkin’s keeping time.
f. Handle pumpkins very gently or they may bruise.
g. If you plan on storing your pumpkins allow them to cured in the sun for about a week to toughen the skin and then stored in a cool, dry bedroom, cellar, or root cellar—anywhere around 55ºF.
C. Treating powdery mildew. Powdery mildew doesn’t require watery conditions to germinate, high humidity is a factor. High humidity fosters spore formation. Temperatures between 60-80 F. (15-26 C.), shade, and high humidity are premium conditions for powdery mildew. If the powdery mildew on the pumpkins seems to be minimal, remove the infected leaves, vines, or blossoms and dispose of them in your waste. Depending upon when the infection set in, this may give the plant enough time to complete production of its pumpkins. If conditions are still favorable for the growth of powdery mildew, it will likely reappear again.
Cucurbits, like pumpkins, are highly susceptible to this disease. Plant them in full sun, allow for good air circulation, and avoid excess fertilizer to try and thwart the disease. Use a slow release fertilizer. It is likely that they will need an application of fungicide, however. Fungicides fall into the categories of protectants, eradicants or both.
There are two oils that work best as eradicants but have some protectant quality as well – neem oil and jojoba oil. Other horticultural oil brands may be used as well. Don’t spray within 2 weeks of a sulfur spray or when temps are above 90 degrees F. (32 C.). Sulfur has been used for centuries to manage powdery mildew in pumpkins and other cucurbits but must be used BEFORE disease symptoms appear. Don’t apply sulfur when it is near or over 90 degrees F. (32 C.) on within 2 weeks of an oil spray.
For an organic method I personally make and use per gallon of water 1 teaspoon baking soda, 1/2 teaspoon pure neem oil, and 1/2 teaspoon dish soap. (Test any sprays before applying to your plants).
Lastly, you can try a biological fungicide (Serenade), which contains beneficial microorganisms that destroy fungal pathogens. It is nontoxic to people and pets and kills the powdery mildew pathogen but isn’t as effective as oil or sulfur. NOTE: Never apply spray before a hot day and fully follow manufacturer’s directions.
Good luck and happy gardening.