Monday, November 24, 2014

Avocados with Black Strings



Why are some avocados stringy?

The strings in the fruit are vascular tissue, part of the conductive system of the plant bringing water and nutrients to the fruit.  They are always in the fruit but are unnoticeable in high quality fruit. From non-grafted trees, or seedlings where a genetic mix takes place, fruit can exhibit darkened, thicker strands as a natural characteristic, especially as it reaches maturity and beyond.  

These strands are usually the same color as the fruit pulp but can discolor or blacken for various other reasons. The most common reason is cold temperatures. This is true in avocado growing in areas like California where temperatures can reach freezing or below. Cold weather, however, would not apply to fruit growing in tropical regions such as the Hawaiian Islands. 

The blackened vascular tissue can also be caused by a disease. There are a number of fungi which enter an avocado at the stem end of the fruit.  Some of these pathogens will cause vascular discoloring as a precursor to decaying the flesh. 

These stem-end rotting fungi are present in the soil and on dead plant tissue and assist in the breakdown of organic matter. The spores of the fungi spread by wind and splashing water. This disorder is clearly made worse in a rainy environment. Infection typically occurs when the fruit is still on the tree, but it does not develop until after the fruit is picked due to anti-fungal compounds present in unripe fruit. Fruit will continue to decay as it ripens.


Control Measures For this Fungal Disorder 
  • Clean out dead limbs and twigs which helps to reduce the incidences of fruit rot.  
  •  Keep trees healthy with proper nutrients and water.
  • Maintain a thick layer of mulch under the tree’s canopy which will help to minimize the disease.   
  • Place avocados in the refrigerator after picking them, if not eaten soon. Caution: Temperatures below 41 degrees Fahrenheit can cause fruit injury in some varieties.
  •  Spray trees with a copper fungicide to limit infection if the problem is severe.

Monday, November 17, 2014

Hummingbirds and Pollination





 

About 25% of plants are wind pollinated. The rest rely on pollinators: bees, bats, beetles, butterflies and yes, hummingbirds, as well as some other birds. During the day hummingbirds feed about every 10 minutes and consume up to 2/3 of their body weight from the nectar of plants; they can service 20 flowers per minute. The wings of hummingbirds beat up to 55 beats per second and allow these tiny birds to fly at speeds up to 50 mph. They can hover and even fly backwards or upside down. 

Hummingbirds are primarily attracted to tubular flowers. They are stimulated by color, especially the color red. Clumps of bright red, orange and pink flowers are more visible to them than other colors. Plants with red, tubular shaped flowers are an excellent choice in the garden to attract hummingbirds. Other plants that attract these birds are gladiolus, honeysuckle, iris, lupine, nasturtium, petunia, and cosmos. 

Lastly, I was asked if hummingbirds pollinate vegetables. I am having difficulty finding specific vegetables that they pollinate. That’s probably because there are not many vegetables with red, tubular shaped flowers, which attract the hummingbirds.  

Photo: University of Maine

Monday, November 3, 2014

Watering Houseplants




How often should I water my houseplants?
  • Although is may seem the easiest method, do not water plants by the calendar. Using this method would assume that in regards to environmental conditions (temperature, humidity, wind etc.), each day of the year will be the same.
  • Water by inspection of the soil or potting mix. If it is wet, wringing wet, don’t water; if it’s dry, water. If the soil is moist, but not soaked, wait a few days and check again. If you actually observe the plant wilting, you should have watered yesterday. When assessing the soil, do not examine the surface, which usually dries out rather quickly. To truly evaluate the condition of the soil, place your finger about a third of the way down the pot or take a mini trowel and pull up some dirt. In reality, you may end up watering somewhat by the calendar, but at least you will have arrived at it through observation and inspection. 
  • The lifting method also works well. If the pot isn’t too big, simply lift the pot off the ground, if it’s heavy, it’s got plenty of water. In comparison, if it’s relatively light, it’s time to water. Putting these methods together, you’ll soon get the hang of it.

A major problem lies in the fact that wilting and lack luster growth can be symptoms of both under watering and over-watering. In the case of over-watering, the roots will begin to rot, with or without the help of soil pathogenic fungi. Once some of the roots are gone, the plant will not be able to pick up enough water, especially on hot days, and the leaves wilt.

It is important to note that under watering a plant will lead to lackluster growth and low fruit production (for fruit producing plants), but over-watering can easily lead to the death of the plant.

As you can see knowing when to water will take some trial and error. It is important to use a well-drained potting mix and never leave water standing in the tray. Plants that have been in the pot a long time may have become pot bound, meaning that most of the space in the pot is occupied by roots rather than soil. If this is the case, you will find that these plants need very frequent watering because there is simply no soil to help hold the water.