Market Farming

["Bill Shoemaker" <wshoemak AT inil.com>]

The slitted stuff opens as the air under the tunnel heats up, and closes as
it cools.
>
>Anyone done any comparison of these two types? How about reusing it? Seems
>to me that if it is only in use for a few weeks, the plastic shouldn't
>deteriorate too much and it might be reuseable.


    Reusing plastic tunnel materials is tricky. If you apply it right, it's
tight, almost stretched over the hoops with the edges buried in the soil.
Those buried edges often rip or weaken when the plastic is removed. Even if
you're careful you may not be able to save it. The scale of your operation
will probably determine whether it's worthwhile or not.

>
>Also what kinds of problems do you have with the wind? Is it anyworse than
>"cloth" rowcover? I'm thinking it might have problems since it essentially
has rips in it for the wind to grab.

    If the material is stretched tight over the hoops and the edges of the
plastic are secured well in the soil the cover will take a strong wind well,
even with the slits. Stretching it tight helps the vents work right too.
When it's cold they shrink a little bit, effectively closing up the vents.
When it's hot, they stretch, which allows hot air to escape. I think the
slitted type works more efficiently than the plastic with holes for that
reason. However, if your crop is not "warm-loving" like cucurbits are, it
might become stressed under clear plastic tunnels. In that case, the
spun-bonded poly materials ("cloth", innerfacing, etc.) will work better
because they don't get as hot underneath.

Bill Shoemaker
Sr Research Specialist, Food Crops
Univ of Illinois - St Charles Hort Research Center