by Yvette Henson
San Miguel Basin, CSU Extension
Summer squash and cucumbers are generally two of the easiest
and most productive veggies to grow in Colorado gardens, provided they get
enough warmth.
Winter squash can be a bit more difficult because they need a long season to mature fruit. Even though they are easy to grow, given the right conditions, they are not without
problems.
In the last two
weeks, myself, my Mom and my friend Pam, have experienced thrips on cucumbers,
blossom end rot on summer squash and squash bugs on winter squash.
Thrips are very small, slender insects with feathery
wings.
Western flower thrips feed on
hundreds of species in our area, including cucurbits (name for all squash, pumpkins, gourds, cucumbers, melons).
They have piercing, sucking mouthparts and
feed on buds, flowers and leaves, weakening plants and deforming fruits.
They can transmit virus diseases.
They can also fill a beneficial role and feed on spider mites but that isn’t
comforting to me right now-- It's my 2 precious cucumber plants that are
infested.
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| Thrips on cucumber flower |
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| Thrips feeding damage on cucumber leaf |
Thrips thrive in hot, dry conditions—just what I have been experiencing
so far this summer.
Cultural controls
are to spray the foliage when watering to create a more humid environment and
to remove weeds in the area that may be alternate hosts for thrips.
Also, don’t apply too much nitrogen
fertilizer, which encourages thrips population explosions.
(Ooops!
I was just trying to get my plants to grow fast so I could get fruit in
my short-season!)
Other control
options for thrips, including organic and inorganic pesticides, can be found in this publication:
http://ipm.ucanr.edu/PMG/r116302111.html Research any
and all insecticides before using to be sure that they won’t kill non-target beneficial
insects and remember to always follow the label!
Tomatoes
aren’t the only ‘vegetable’ to get blossom end rot.
My Mom ended up with blossom end rot of her summer squash (see photo). The cause of blossom end rot is insufficient
calcium uptake by the plant due to inconsistent moisture levels in the
soil.
This is not the same as a calcium
deficiency in the soil.
It is more
common on the first fruits of the season.
On rare occasions, it can be caused by insufficient pollination.
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| Blossom end rot on summer squash |
To prevent blossom end rot, water regularly and evenly to
about 6-8”deep – don’t allow soil to dry out too much between watering but don’t
allow soil to be waterlogged either.
Something
else to try that seems to have worked for me is to apply a liquid Cal-mag
fertilizer occasionally.
See this
publication for more information on blossom end rot on veggies:
https://www.canr.msu.edu/news/blossom_end_rot_causes_and_cures_in_garden_vegetables
I live in the mountains so my cucurbits are just starting to grow and
bloom. My friend Pam lives in Olathe, a
much warmer climate, and her
warm-season veggies are starting to produce. She hasn’t been home much because of work, so she
asked me if I wanted to harvest some of her garden. Why, of course! Thank you, Pam! When I wasgleaning from her garden, I noticed that one
of her squash plants was wilted. At
first, I thought it was squash vine borers, but I couldn’t find any larvae or frass
inside the base of the wilted vine. On
second inspection, I found 4 dreaded squash bugs!
|
male and female squash bug (I interrupted their mating to take this photo)
|
|
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| 2 of 5 winter squash plants showing wilt symptoms from squash bug feeding |
Squash bugs can be found most commonly on winter squash and
pumpkins but they sometimes feed on summer squash, gourds and melons.
They lacerate plant tissue when they feed,
causing rapid wilt and eventual death of the plant.
One thing that Pam could have done to reduce
squash bugs was not to use the black plastic mulch as weed control.
Mulch gives the squash bugs more places to
hide.
She decided to use an insecticide
she already had that was listed as a control in this fact sheet:
https://extension.colostate.edu/topic-areas/insects/squash-bug-management-in-home-gardens-5-609/ The sad thing is she will most likely lose
most of the plants that are already infested. The original affected plant I saw progressed to 5 affected plants in just a week!
More information about other problems one might experience
when growing other cucurbits, not jsut squash and cucumbers can be found below.
In instances where there are not enough pollinators or plants
are grown under season extension covers there may not be pollination and fruit
set
file:///C:/Users/YvetteH/Downloads/FruitSetProblems.pdf
Cucurbits can also be attacked by cucumber beetles, aphids, spider
mites and powdery mildew and more!
https://hgic.clemson.edu/factsheet/cucumber-squash-melon-other-cucurbit-insect-pests/