I'm in south jersey. This year was horrible for powdery mildew and other diseases. Many commercial growers lost entire fields. I would not blame the wood chips just yet. You can sign up for email alerts from Rutgers.

http://plant-pest-advisory.rutgers.edu/

Very accurate and helpful. Their reports can alert you to what to look for and tell you what is going on in your area.

I just pulled all my squash/melons since they were mostly lost to mildew. I am getting ready to put in cover crop and hopefully next year will be better.

Still something to learn.

My pumpkins have vine borers. Most of the Japanese Kabocha are lost since I caught them late. But the regular orange pumpkins are doing fine since they sent out strong stems. The 2nd batch Kabocha is doing fine.

The peppers still are very green, but lost leaves quickly (yellow with black spots). Not sure if fungus or diseases. Some small flies, but I do not think that is is the problem.

The tomatos are producing, but the lower leaves turn yellow and dropped. Now 2/5 of the lower leaves fell. The plants are about 5' tall. Lower yield than last year's.

The water melons were doing great. Then stopped growing. I did not see any bugs. Then the leaves turned yellow with black edges. Then the whole vines just died. The melons are about sugar baby size or smaller.

The blueberries did very well. Better yield than last year's. I think the wet weather somehow helps.

Anyhow, still something to learn for next season.

There is a fungus that grows in wood chips call Mycelium. It is a white tiny thread like looking thing.

Wood remnants grow fungi dedicated to the breakdown of dead materials. As far as I know, this is an entirely separate plate of beans from the predatory things that may be affecting your living plants. For instance, the two main "mildews" that affect cukes may gather in wood chips but they would also do the same in bare dirt, straw, pine needles, old gloves, and so on. The spores are everywhere, but wood is no magic safe nurturing harbor for them.

I have used wood chips for the paths, not the beds, of my permanent bed garden for many years. I use hay, not straw, around the veggies. No problems.