Monday, June 24, 2013

Transplants vs. Direct Seeding

Should gardeners plant vegetable seeds directly into the ground or plant them in small pots first, then transplant them into the garden?  
Some vegetables need to be direct seeded, while others are best transplanted. But most vegetable plants do well either way.

In general, transplants are easier to care for.  They are usually started in a more controlled environment - a greenhouse or some type of sheltered area.  Here, the seedlings are better protected from soil diseases, especially when a sterile potting mix and clean pots are used. A greenhouse offers protection from insects, animals digging up the ground and environmental stresses like hot winds and cold temperatures.  In cooler areas, seeds can start in a warm  environment and later be transplanted outdoors. 

Yet from time to time transplanted vegetables suffer from transplant shock. When the seedlings are set into the ground, the roots are damaged in the process. Plant growth is delayed until the roots recover. 

Certain plants can regenerate new roots quickly and as a result transplant easily; they include broccoli, brussel sprouts, cabbage, lettuce and tomatoes. On the other hand, cauliflower, celery, eggplant, onion and peppers are slower to regenerate, but they can still be successfully transplanted. The cucurbits (cucumbers, melons, squash, etc.), legumes (beans and peas) and corn have even slower root redevelopment, but if root disturbance is kept at a minimum, they will do fine. 

Vegetables that have a taproot like beets, carrots and turnips should be direct seeded.  Transplanting these vegetables will cause deformations and undesirable lateral root development. 

Monday, June 17, 2013

Control of Mealybugs

In general, mealybugs are under good biological control. That is, because of the presence of a number of predators and parasites, this pest population is kept low.  There are, however, a number of factors that upset this balance. Two important factors are: the application of broad spectrum insecticides (BSI) and ants.  The application of BSI will not only kill the target pest but “the good bugs” as well.  When this happens, the resurgence of the pest can be worse than before. In addition, other pests, such as mites, will become a threat because their enemies have been eliminated.  

Ants also interfere with biological control because they protect the pest from its enemies.   By controlling the ants, the mealybug population will eventually diminish as the predators and parasites return. Although it takes time to work, even a couple of months, baits can be effective in controlling the ants.

For a quick solution, mealybugs may be sprayed with a soap and/or oil solution.  In addition, a high pressure stream of water from a garden hose will dislodge many of the pests.

Added note: mealybugs have filaments, or hairs around their body which protect them by repelling the spray droplets of  insecticides. Consequently,  a ‘spreader/sticker’ should be added to the spray solution. This product acts like soap to break down the surface tension and allow the liquid spray to spread out.  Spreader/stickers are necessary with most insecticidal applications but not when using soap and/or oil sprays. 

Photos by J.K.Clark, UCIPM

Monday, June 10, 2013

The Difficulties of Growing Spinach

For many gardeners, it’s a matter of throwing the spinach seed on the ground and later harvesting a plentiful crop. Yet others struggle; here are a few reasons why:

1. When growing spinach, knowing the soil pH is important. Spinach is sensitive to highly acid soils. The soil pH (acidity/alkalinity) should range from 6.4 to 6.8.  When the pH drops too low, the following symptoms can occur:  low germination, yellowing, slow growth, browning of the margins and tips of seedling leaves and even death of the plant. If the pH is too high, leaves may have a general yellowing (chlorosis).

 A pH of 7 is neutral, above is alkaline and below 7 is acidic. A soil analysis will reveal the pH.  If needed, adding lime will slowly raise the pH of the soil.  If a soil is alkaline, sulfur is added to lower the pH.

2. Most spinach varieties are susceptible to cucumber mosaic virus (CMV).  Symptoms include a slight chlorosis of younger leaves along with narrow or "puckered" young leaves. Leaves also can have an inward rolling of margins. In advanced stages of the disease, the plants often appear stunted. Melody F1 and Savoy hybrid 612F are reported to be resistant to CMV.

3. Spinach is a cool-season vegetable and belongs to the goosefoot family (Chenopodiaceae) along with beets and Swiss chard.  They thrive best during the cool, moist seasons of the year. During periods of warm weather and long days, the spinach plant will bolt - stop its leafy growth in favor of flower and seed production. The Tyee variety is one variety that is slow to bolt.

4. And lastly, it is important to use new, fresh seed each year. Spinach seed that is more than a year old, rarely germinates over 80%; the germination rate diminishes with each year. Beet seed will germinate in temperatures as low as 380F, but good germination for spinach is between 50 and 60 0F. High soil temperatures result in reduced germination. Spinach is a cold-hardy crop and can withstand temperatures as low as
20 0F.

Spinach can be grown successfully on a variety of soils, but a fertile sandy loam high in organic matter is preferred.

Ask the Garden Guy Science Based Answers to Garden Questions, is an excellent resource book for the gardener. Some popular topics include Slugs and Snails, Organic Pesticides, Reasons, Why Vegetable Seeds Do Not Germinate, What’s So Hot about Manure? and Mushrooms in the Lawn.  Purchase by clicking on the image of the book above.