Thursday, July 26, 2012

Heat Stresses in the Vegetable Garden


Summer has been extremely hot in Kit Carson County this year and I have been fielding a lot of calls regarding tomatoes that are not setting on blossoms.  Tomatoes do not need a specific day length in order to flower.  Temperature is the determining factor. The optimum temperature for fruit set is 65 to 80 degrees F.  Wide swings in temperatures from day to night such as we are experiencing (95+ day to 65 night) have an adverse effect on blossom set, sometimes causing plants to drop their blossoms.


 Tomatoes, eggplants and peppers are all affected by the high temperatures with a condition called “sticky pollen”.  The heat changes the shape of the pollen proteins and makes it difficult for the pollen to leave the anthers (the part of the plant where it is produced).   Even though it seems like we have plenty of wind to move pollen around, the plants will do well with a gentle shake from the gardener!  The best time to shake your tomatoes, eggplants and peppers is early morning or late evening.  Coincidentally this is also the best time to be watering in the garden. 


Keep in mind that fruit production in the garden requires more nutrients.  Approximately 40 to 50% of the nitrogen requirements for tomatoes can be added to the soil before you even plant the garden.  But if your soil is less than 3% organic material, you may need to add nitrogen during the growing season.   Now is a good time to feed the garden with a water-soluble nutrient, especially one that includes potassium.  Potassium will improve the quality of the produce as well as help the plants better utilize the water you are applying.  Follow the instructions on the package for proper application.


Since the fruit is about 95% water, tomatoes use large volumes of water during fruit set.  As much as 1.5 to 2 quarts of water per plant per day may be needed from fruit set to harvest!  Irregular watering may result in cracked fruit.  Mulching and regulated lengths of watering time can help with this important aspect of gardening.


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Article by Lisa Brewer,  Colorado Master Gardener



Cottony Oak Gall

Cottony Oak Gall picture by Linda Langelo

The picture above are the galls produced by the cynipid wasp in the Hymenoptera Family.   These wasps are very difficult to control.  They are always found on the undersides of the oak leaves. They are often woolly with a white-tan color and along the midvein.   The wasps usually pick bur oaks or Quercus macrocarpa as the host.   The picture below shows the wasp.


In the spring when the leaves are newly expanding, the females lay eggs in the leaf and the new larvae cause abnormal growth development of the galls by injecting plant growth regulator chemicals.  This growth is a reaction to the chemicals.  Once the galls are formed, this protects the developing larvae.  The insect becomes difficult to reach.  Overall, plant mortality is often low.  The best control of these wasps is other wasps that parasitize them. 

Monday, July 23, 2012

Our Living Soil

Our topsoils  normally contain about 1% organic matter.  According to professors in the Department of Crop and Soil Science in Cornell University and University of Vermont,  as organic matter decreases in our soils, it is difficult to grow plants.   What happens?  Below is the list of negative impacts to our soil without organic matter applied regularly:

  • Water retention lessens
  • Fertility lessens
  • Compaction increases
  • Erosion increases
  • Parasites, diseases and insects also increase
Then what happens.  We spend money to control the parasites, diseases and insects.  We spend money to divert the eronsion and possibly loose crops.  Then there is still the compaction and low fertility.  We apply other fertilizers and other expensive fixes to help alleviate. 

Soil is a living organism. 

Tuesday, July 17, 2012

Time to plant for your fall garden

Do you like cabbage or broccoli?  How about spinach?  These are just a few of the cool season crops you can grow in your garden, if you are not too tired from growing all the cool season crops in spring and then the warm season crops in summer. 

If you don't do well with growing the cool season crops in the spring, what would be the point of doing it again in the fall?  Here are few things to consider:

  1. Temperatures are more tolerable.
  2. Fewer pests.
  3. Frost enhances the flavor.
  4. Frost increases the sweetness of the kale and collards.
  5. Less weeds. 

Overall, fall garden is much easier and less effort.  So start sowing the seed!   Here is a list of crops to try:

  • Broccoli
  • Cabbage
  • Cauliflower
  • Spinach
  • Kale
  • Collards
  • Lettuce
  • Spinach
  • Escarole
  • Endive
  • Brussel Sprouts
  • Leeks
  • Oriental Vegetables
  • Garlic
  • Arugula 
  • Mustard
  • Turnips
  • Kolhrabi
  • Rutabaga

Be sure to check on the final hard frost and count back 8 to 12 weeks.  This will give you from 56-84 days or so.  With broccoli, cabbage, cauliflower and brussel sprouts it is best to start with transplants.  These crops are referred to as cole crops or crops in the Cruciferaceae Family.  This also includes mustard.  Most recently, the family is now referred to as the Brassaciae Family.  All the flowers of these plants have the same flower parts.  Think of it this way.  All the flowers in the pea family have the same parts whether the flowers are on an edible pea or a sweet pea flower or another member of the family. 

For broccoli, cabbage, cauliflower, brussel sprouts, kolhrabi and kale, start the seeds in mid-July.  Use starter fertilizer on the transplants.  This can increase your yields by 20%.  The preferred growing temperatures are 60 - 70 degrees.  In a more mature stage, broccoli and cauliflower can tolerate some frost.

All the cole crops are intolerant of dry soils.  They are shallow rooted and like moist, well-drained soil.  If the soil drys quickly, these crops can acquire a stronger flavor.

Unless the snow in northeastern Colorado comes early, fall crops can bring you a great harvest.  With garlic, leeks and spinach, these crops can winter over.  Brussel sprouts can produce a harvest into December. 

The oriental vegetables are similar to the cole crops in their cultural practices.  It is recommended to side dress with calcium nitrate three weeks after planting at a rate of 1.5 to 3 lbs per 100 foot row.  For any of the root crops listed, side-dress with ammonium nitrate for 30 days prior to harvest.  Before preparing the planting area, the best recommendation is to have your soil tested.  Then you have a baseline.  You can make more accurate adjustments.

Happy fall gardening!  Be sure to contact your local Extension Agent, if you need more information or have any questions. 


Thursday, July 5, 2012

Echinacea Disease



Ever heard of a phytoplasma?  These are single celled microorganisms that live in the phloem of plants.  This phytoplasma is similar to a bacterium. This phytoplasma has no cell wall.  It can infect over 300 plants in 48 different families.  Some of those plants are listed below.  The picture above is typical of aster yellow in Echinacea.  Picture taken by Linda Langelo, Horticulture Program Associate in the Colorado State University Extension, in Golden Plains Area.

One of the more well-know phytoplasma is called aster yellows.  This is vectored by the aster leafhopper and other leafhoopers.  This leafhopper migrates from the southern United States to the northern United States.  It is seen annually in many northern gardens. 

Weeds such as horseweed, dandelion and Queen Anne's Lace can harbor the aster yellows phytoplasma.  There is an incubation period of aster yellows within the leafhopper before it can tranmit the disease.  This also occurs within the plant before the disease appears.  The leafhopper feeds on plants that already have the aster yellows or the casual phytoplasma.  The disease circulates in the leafhopper's body.  When it reaches the leafhopper's salivary glands will it be able to transmit the disease.  The time frame for this to occur can be from 10 days to 3 weeks.

Aster yellows has many hosts besides the weeds mentioned above.  There are many ornamental plants and vegetables.  Among the ornamental plants are asters, anemone, centaurea, chrysanthemum, coreopsis, delphinium, echinacea, gaillardia, limonium, phlox, scabiosa and veronica.  Among the vegetables damaged by this disease are head lettuce, carrots, New Zealand spinach, cauliflower, cabbage, dill, endive, escarole, onion, parsley, parsnip, potato, squash, tomato, pumpkin and celery.  With all of the different crops listed above, the lettuce and carrots are effected over other crops. 

Removing the infected plants is the most effective help control the disease along with growing less susceptible plants.  These plants include nicotiana, geraniums, salvia, cockscomb, portulaca, verbena and impatiens.   Remove weeds within the garden area.  Some weeds are symptom-less and can harbor the disease.  The leafhoppers will carry the disease for their lifetime.  The leafhoppers are difficult to manage in the home garden.