Friday, September 16, 2011

Butternut Squash and Growth Cracks.

As autumn approaches butternut and other winter squash (to include pumpkin) develop a hard skin. This permits the storage of these fruits for several months. Once this hardening process starts anything that encourages further growth of the fruit may result in splitting of the fruit as is seen in these photos. A heavy rain or application of water after the fruit starts to harden its skin can stimulate growth and result in the cracking of the fruit. Applying nitrogen at the wrong time can also cause splitting.

Vine crops like butternut squash should be side-dressed in midseason as they start to vine. At that time 2.5 ounces of nitrogen should be applied for each 250 feet of row. Fertilizing much later or with more than recommended above can stimulate growth resulting in cracking. See for details on fertilizing vegetables in the summer.

The crystalline substance on the edge of the cracks is due to plant juices that oozed from the damaged tissue.

Thursday, September 15, 2011

Pearleaf Blister Mite - no need to spray now!

The pearleaf blister mite has been feeding on pear leaves all season.  The damage it causes is minor even though the leaf below appears to be devasted by this mite.  At this time of year there is no reason to spray as the leaves will be dropping soon anyway. 

Under side of the leaf

You can prevent this damage from being severe by treating your pear trees with a dormant oil spray in the spring just as the buds start to swell and the first hint of green appears.  For a more indepth spray guide, check out the publication at

Upper surface of the leaf.
These mites live inside the leaf between the upper and lower surfaces.  To see how they get into the leaf check out

You can enhance winter hardiness of your grape vines by proper fall watering

How do you ensure your vineyard, whether consisting of acres of vines, or just a few vines in your back yard, has the best chance of making it through the winter without suffering winter damage?

At this time of year (September) you should stop watering your grapes to encourage them to acclimate properly for winter. While you can’t control the rains you can certainly turn off the watering system to your grape vines for the next month. If your vines are less than one year old watering should have been stopped by mid-August or even earlier. Young vines are much more vigorous than older vines and need more encouragement to acclimate properly for winter. Withholding water provides that encouragement. You should also avoid the application of any nitrogen fertilizer at this time of year as this can stimulate growth resulting in winter damage.

 After the first fall frost (but no sooner than October 15)

Turn your irrigation system back on and thoroughly water the vineyard. The roots of your grapes may be three, four, or five feet deep thus it may take hours to apply enough water to fill the soil profile to the lower depth of the roots.

Drip tube running along the lower wire of the trellis.
If your grapevines are irrigated by a drip system you may need to water for 8 to 10 hours per day for three days to apply adequate water.

If you are using a sprinkler system apply a foot of water. Apply it slowly to allow it to be absorbed by the soil and not run off. Many sprinkler systems apply an inch of water or more per hour so you will need to turn off the sprinklers. This is much too fast for the water to be absorbed by the soil.  When the water starts to run off. Wait an hour and turn the system back on. You may have to do this a number of times to apply the amount of water needed by the plants to carry them through until spring.

Ditch vs. Domestic Water
If you use irrigation water the ditch may be shut off before mid-October requiring you to irrigate earlier than the first frost. If you have access to treated water, delay this last application of water of the season until after October 15. Don’t make the mistake of using well water or water from a drain ditch to irrigate your vines unless you have tested it for salts and the sodium adsorption ratio (SAR) and been approved for irrigation use. Once you have watered for the last time of the season be sure to winterize the system to avoid winter damage and costly repairs next spring. If the winter is open and dry watering your vineyard in mid-winter is recommended.
The first fall frost in Mesa, Delta, Montrose, and Ouray counties varies with the community as can be seen on the web page at .

Information on SAR is at

See the fact sheet on winterizing your irrigation system at

Information on winter watering is at

Tuesday, September 13, 2011

Tomato Zippering

Sometimes damage to the fruit of a tomato plant can be caused by the weather. Zippering, obvious from the thin, brown, dead scar running from the stem scar down the side of the tomato, is one weather related problem we are current seeing.

Sometimes a small protrusion develops at the end of the zipper. Formed by anthers, the male parts of the flower, sticking to the newly forming fruit, zippers are more common when early fruit development occurs in cool weather.

Sometimes a hole opening into the locule forms. In this instance there is a small hole but it does not extend into the locule.

See for what happens when the hole extends into the locule.

Monday, September 12, 2011

Leaks in Irrigation System may be obvious.

Sand and gravel on the sidewalk can be evidience of a leak
in your underground irrigation system.

Soil and gravel is being flushed onto the sidewalk by a broken sprinkler head or broken irrigation pipe. Note the area washed clean by the leak and the dirt on either side. This leak needs to be fixed or the concrete sidewalk will be undermined and fail. The repair will also help reduce water use. When you notice something like this happening be a good neighbor and let the owner know.

Note where the water is flooding out between the sidewalk and grass and has washed the sidewalk clean.

Closeup of point where water is escaping to the surface.