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Grittyville, WA

Does a colder winter boost weights? Any ideas about winter weather affecting pests or soil biology? Does freeze/thaw have a good or bad soil-improving effect in terms of results? I wonder what you think is the perfect winter weather, going with the calendar definition through March 21, in terms of most people getting better results? But I realize that summer weather has a more direct effect.

1/14/2019 11:03:30 PM

Syracuse, NY

i would suspect that a very cold, long winter would do well to help to immobilize any soil pathogens that would otherwise survive and be a threat to us in the continuing, following seasons of any 'not-that-cold' winter; i do believe that if you do not freeze FOOD well enough that it, too can become a danger to eat, so, applying that idea to SOIL, in which biologicals live and try to survive all perils...just MHO---eg---just grow them hardy Gerry seeds, lol!---EG

1/15/2019 3:58:41 AM

Morgantown, WV

Not to be combative, but I just finished my Plant Pathology course, and my brain hurts after that last statement.

Many pathogens (as you might guess) are designed to survive the extremes to last in the environment. Phytopthora is a common disease that gets spoken about often here, and it is an oomycete which forms incredibly resistant overwintering structures that not only affect host plants, but will lay dormant on perennial weed roots as well. You will not control it through crop rotation, and once you have it, it is incredibly difficult to eliminate completely without fumigation and major cultural changes to your program.

Powdery mildew will overwinter in mature structures called cleistothecia. Again, very resistant to unfavorable conditions, but warm and wet always bring it back as it is water and wind spread. Unless you can remove any leaf in your area that may have had PM on it (pumpkin OR any of the hundreds of other host plants for it) it will survive even cold winters to return as primary inoculum when the weather is right.

While extended cold may have a slight effect on insect populations, it won't affect much else. Your biology is natural based on your soil and climactic history. They too, have evolved to settle down in the winter, but come back full force when conditions are right.

If you are having a mild winter, yes, you will probably have higher disease pressure than normal only because the conditions are closer to their favorable zone. The longer it takes them to break dormancy, the farther into the season you get before having to deal with it if that makes sense.

My best suggestion for dealing with winter weather is to go to your local university's Extension Services site and read some educated material on the questions you have. THEN come back here with what you don't quite get, and you'll probably get better results than hypothetical situations will give you.

1/15/2019 7:04:27 AM

Bethlehem CT

In all my years of growing I have never seen any correlation between a hard winter and less disease. Also I have never seen any fewer insects from a cold winter. I always just bite my tongue when I hear people say we need a cold open winter to kill the ticks and insects. I personally don't think it makes any difference based on my experiences in my location.
However, the winter freeze thaw cycle can help to break up compaction.

1/15/2019 7:23:50 AM

stoughton WI

Good info dustin, winter freezing also had little effect on lessening fusarium and pythium pressure in our patch. Early high heat also kicked into high gear sooner makkng it more difficult to control. I was under the understanding from the research that i have done, that p.m. will not over winter in the soil. It was more so brought in on the trade winds. My guess we be from the southern states where they dont get frost in the ground.

1/15/2019 7:54:39 AM

Morgantown, WV

Correct Rick, the mycelium of PM will not overwinter in the soil, but if it got to the mature stage of producing sexual fruiting bodies, those will overwinter in the soil or on other plants (grass, weeds, surrounding trees' bark, etc.)

PM is also a multi-cycle type of disease, where there is a primary infection early in the season ( overwintering sexual spores) but also subsequent infections of higher magnitude due to a short reproductive stage and exponential growth. The fact that it has subsequent infections over a single season tells us it does not take long to reach that stage, so often even late infections in the patch will render sexual spores that will fall when the old vines are cleaned up.

I believe the most impactful reservoir of PM is actually our neighbors. Though we here generally tend out gardens well and try to improve cultural practices whenever possible, your neighbors don't. In Spring, shortly after the peonies bloom, watch them fall apart by un-checked PM. Look in people's herb gardens this summer where they planted in spring, lost interest, and now the crowded growth is causing outbreaks.

PM is difficult in that it infects an incredibly large number of species, and often times at least one of them is close by in proximity whether you are aware of it or not. Additionally, your neighbors may not clean the infected debris away even if they do notice it, which invites buildup over short periods.

I apologize to be long winded here, I'm just trying to share what I believe to be correct info about this as I've had access to it recently. These reasons are why I myself choose to treat with systemic prior to infection, rather than trying to knock it down only after I get it.

Ounce of prevention over a pound of cure.

1/15/2019 9:02:14 AM

Weatherman

Snow acts as an insulation your ground won't freeze deep.

1/15/2019 9:12:31 AM

Morgantown, WV

I should add two things:

The subsequent infections are not the sexual stage that is reached as it gets older, but the initial infection then becomes the sexual stage as the younger generations spread the non-sexual stage through conidia. Conidiospores of PM are different from most spores in that they do not need free water to infect, just a living host, so dry leaves are not enough for effective management.

Also, once infected (not yet at the visible stage until conidia are formed creating the white appearance) PM will form "haustoria" which is sort of like sticking your finger inside your belly button. It penetrates inward, but does not actually break the cell wall, only enlarges. These will release hormones to actually change the metabolism of the plant in order to channel carbon to the PM (and away from your fruit) for food. As it progresses, it lays a multitude of these into the leaf surface and chlorosis begins when the leaf starts to get tired. PM needs a living host, so only steals what it needs, but growth is affected prior to the point it can be seen by the naked eye, and is why it is difficult to get rid of once you have it.

1/15/2019 9:20:14 AM

Anamosa, IA BPIowegian@aol.com

Cold winter weather does effect insects, which may reduce insect borne diseases. The 2017-18 winter here was very cold, and the cucumber beetles and squash bugs that were terrible in previous years were not much of a worry in 2018. I didn't get the diseases that they were spreading.
But it did nothing to slow down soil borne problems. I would think that just the opposite, excess heat, like from solarization, would knock out disease. I worked one spring in a greenhouse around 1970. They had a special bin set up sp they could inject steam into their potting mix to kill diseases and weed seeds.

I have found that high humidity and low wind speeds speed up air borne fungal diseases like PM and the brown rust that gets long gourds. That is why August is the worst month in Iowa. Our millions of acres of corn are pumpkin lots of water into the air, and that is the month with our lowest average wind speeds. Add in the fact that my garden is in a valley where the wind is slowed down, and humid air sinks in after sunset, I really dread August diseases.

1/15/2019 9:43:22 AM

Arden, NC

Dustin, that's why I like the use of silica in Compost teas and foliar application of the same. Silica boosts the epidermal wall thickness of cells, reduces the interstitial volume between cell walls making it harder for things like Pm to take hold. Additionally the chewing bugs hate it on the plant leaves and will vacate the treated areas.

1/15/2019 5:38:51 PM