Tuesday, March 24, 2015

Citrus Care: Gearing up for the Next Crop

Fig. 1    Flower buds and new leaves emerge as the temperature rises.

As the California temperature rises, the once cold-beaten citrus trees are now on a rebound.  New buds are starting to surface from under last-year's foliage - promising another bountiful crop (Fig. 1).  In order to have that promise materialize, there are a few things to keep in mind. 

Factors to Consider All Year

Sunlight.  Citrus plants need long hours of sunlight.  Make sure they get at least six hours of good sunshine everyday.  

Soil Nutrient.  Citrus are heavy feeders.  Apply fertilizer during the early spring.  In my garden, I use 16-16-16 in late winter to replenish what was spent during fruiting and to give them an early starter food for spring.  Repeat fertilization once a month and give them a dose of fertilizer containing micro-nutrients - especially for plants grown in containers.  
Soil Moisture.  Contrary to popular belief, citrus plants require moderate amounts of water.  Water them regularly in the early spring to ensure excellent fruiting.  Fruit-set is highly dependent on optimum water during flowering to fruit set.  

Fig. 2  Allow the trees some rest by harvesting the last season's fruits.

Things to Look Out for in Spring

Last season's fruits.   Citrus fruits are beautiful and unlike other fruit trees their fruits do not abscise readily.  If you have not done it already, it is time to harvest the remaining fruits to allow the plants to completely focus their resources into the development of the new crop (Fig. 2).  

Suckers/Water Sprouts.  Water sprouts also known as suckers are a natural occurrence in citrus plants.  They are vigorous young branches growing vertically which often come with thorns (Fig. 3). They are healthy-looking but if allowed to remain, they will exhaust huge quantities of resources such as water and nutrients at the expense of the rest of the plant.  Therefore, cut off water sprouts as soon as possible.

Fig. 3  Water sprouts are vigorous growth with 

Fruit Drop.  Flowering and fruit set directly affects final yield of citrus plants.Under favorable conditions, citrus plants generally set more fruits than they can support and at some point, the tree will naturally shed some of the tiny fruits (usually the size of jelly beans).  Excessive fruit drop could be a result of water stress.  Numerous studies have shown that water stress influences flowering and fruit set.  Make sure the trees get sufficient soil moisture during these critical stages.

Pests.  Snails, slugs, scales, and leafminer can all pose a challenge to citrus plants.  There are a million options when it comes to pest management.  Nonetheless, success can only be achieved by proper timing.  Control snails and slugs in late winter before they can have a chance to lay eggs or damage plants.  Applying horticultural oils can prevent scale infestation.  Spinosad or Pyrethrin can control the leafminer moth before oviposition.  Still, allowing nature to deal with its own seasonal imbalances is even better.  When pests arise, some insects that are antagonistic to them also flourish.

With a little attention to details, your citrus trees will reward you with a bountiful crop.

Thursday, February 26, 2015

My Cymbidium Photo Gallery 2015

This is the time of year when my cymbidiums are in bloom and thus the obligatory orchid photo-shoot.  The variety names of these ones are not known to me but I will let the flowers speak of their kind.  

New this year - I got it as a gift. 

The only green-colored one in my collection - always blooms earlier than the others.

New this year - Bought from the Farmer's Market in Marina, California

New this year - Bought from an ethnic grocery store in Marina, California.

One of my old time favorites - turns pinkish when the temperatures are low.

New this year - bought from Marina, California.

I've had this for a long time.

Cymbidiums are not only beautiful - they also lasting.   
Try growing one this year 

Wednesday, February 18, 2015

Tradescantia somaliensis: Trichome-enhanced Beauty

Botanical Name:  Tradescantia somaliensis
Synonym:  Cyanotis somaliensis
Common Name:  Kitten Ears, Furry Kittens, Pussy Ears

Fig. 1  Newly replanted Tradescantia somaliensis from a 2-inch pot.

Tradescantia somaliensis  is an evergreen tender perennial with a notable tolerance dry conditions.  It is known to have originated from Somalia, as indicated  by its species name 'somaliensis' although it would not be a surprise to see find out that the plant is also native to other countries in the African continent with similar climatic conditions.

It is a curious plant with pointed (lance-shaped) leaves that are edged with striking trichomes which give the appearance of hairy kitten's ears. It's trailing growth habit and makes it an outstanding container plant (Fig. 2).  When grown outdoors, the plant needs protection from the direct afternoon sun particularly in the hot areas like ours (Zone 9).  For indoor cultivation, choose a bright location to ensure that the plant will remain compact.

The trichomes that line its leaf margins make Tradescantia somaliensis 
very interesting interesting plant.

Fig. 2   Tradescantia somaliensis: Fast-growing yet compact.

Propagation of this plant can be done easily through cuttings and layering.  In my case, I usually take cuttings after blooming period.  That way I get to enjoy the flowers first.

Once a year, try a new plant in your garden and learn about it. 

Friday, February 13, 2015

Guttation in Succulents

Fig. 1  Guttation in Succulent Plant:  Leaf margins of Aeonium 'Pinwheel' studded with xylem sap.

Succulents are known for their ability to hold and store large quantities of water for future consumption.  These plants, which are characterized by their  thick succulent leaves, can store large quantities of water resulting in their ability to withstand prolonged dry conditions. These plants are not commonly known to exhibit guttation - the excretion of water from the plant through hydathodes due to certain atmospheric and soil conditions.  The pictures here (Fig. 1, 2, & 3), however, show that these water-thrifty succulents can have too much water. Given the right conditions, succulents undergo guttation.

  Fig. 2  Succulent leaves crowned with beads of guttation fluid.

Fig. 3  Senecio bearing guttation sap.

Plants are amazing creatures.

Sunday, November 30, 2014

Citrus Leafminer

Fig.  1   Leafminer larvae feeding in the leaf through sinuous mines.

Citrus Leafminer in the Area
Leafminers (Phyllocnistis citrella) appears to be an important pest this year in our area.  As a matter of fact, this is the first time they appeared in my garden.  All my citrus plants - including orange (Citrus sinensis), lemon (Citrus limon) and calamansi/calamondin (Citrofortunella microcarpa) - showed symptoms of infestation during late summer and early fall.

Citrus leafminer is native to Asia and has spread slowly around the world. It is relatively new in the US as it is was first discovered in Florida in 1993 and eventually made it to California in 2000 (1).  It was first detected in Imperial County - probably through Mexico.  It soon moved inward toward adjacent counties (2).  And this year, leafminer now infests Sacramento and El Dorado Counties - including my garden.

Fig. 2   Leafminer larvae: feeling agoraphobic after an opening was made on its tunnel.  

Life Cycle
 Leafminer, in its adult form, is a very tiny moth which are rarely noticed.  They are most active during the cooler time of the day as in early morning and evening - resting on the underside of the leaves of the host plant during the day.  The moth does not do damage to the plant but it lays its egg along the mid-vein of new tender leaves.  After a week, the egg hatches into a larvae and it begins to feed in the leaf creating micro tunnels that runs in a sinuous path of mines (Fig. 1).  Leafminer is most destructive in the larval stage. The once-invisible tunnels soon begin to cover a large proportion of the leaf.  At some point the larvae gets out of the mines and move towards the edge of the leaf and rolls the leaf around it -- this is the pre-pupal stage.  The curling of young foliage is the most noticeable sign of infestation (Fig. 3).  Unfortunately, at this stage, most of the damage has been done.  The pupa will live there for a few more weeks before it emerges as a moth (Fig. 4).  Female moths immediately releases sex pheromones to attract males.  Thus the cycle of life continues without delay. :)

Fig.  3   Citrus leafminer (Phyllocnistis citrella) on Calamansi.

How to Manage Leafminer
The success management depends on how early the life cycle broken. Pest when properly managed can be inhibited from spreading into a large area.  Since oviposition (egg-laying) happens only in the newly opened leaves, it is a good idea to monitor the presence of leafminer around the time of growth flush.  IPM recommends the use of pheromone-baited traps only to detect the time when males begin to fly and determine time of insecticide application. There are insecticides available for the control of citrus leafminers but timing and type of insecticide is key.  

 Depending on mode of action, insecticides attack pests at 
specific stages of  the insect's life cycle.

Here are some examples of pesticides and the corresponding stage of the insect when they are most effective:  

1.  Permethrin (e.g. Eight) and Spinosad (e.g. Captain Jack's Dead Bug) Controls the moths.  Spray only within the area where they are expected to linger.
2.  Horticultural oils (e.g. Neem Oil) May hinders oviposition (egg-laying) on sprayed leaves.  Repeat spraying as new leaves emerge.
3.  Neonicotinoid (e.g. imidacloprid) controls the larvae.  When the leafminer larvae are inside the "leaf mine" only systemic insecticides (such as neonicotinoid) can get them effectively. For drench application, it is important to keep in mind that the insecticide molecules take about two weeks to reach the growing points of the plant - where leafminer eggs are laid. In other words, apply before infestation is expected - when the new leaves are half-way open.  Imidacloprid when sprayed on the leaves can also move translaminary - the active ingredient of the insecticide penetrates the leaf cuticle and moves into the leaf tissues.  This means that even the larvae that is securely tucked in its tunnel becomes vulnerable.

When using any insecticide, always use recommended dosage and the recommended schedule so that we do not accidently kill unintended insects including beneficial ones.
Fig.  4     A magnified image of an adult citrus leafminer (Phyllocnistis citrella).   (Photo from Tirogaverd)

Other Management Tips
1.  Pruning encourages new growth (flush) on which leafminers prefer to lay their eggs.  If you can handle looking at leafminer-damaged leaves, do not be too in a hurry to cut them off because they can still continue to photosynthesize (produce food) for the plant. 

2.  High-nitrogen fertilization also result in a growth flush.  Avoid excessive nitrogen application and  use organic fertilizers or slow-release fertilizers. 

Stroll in your garden often.  If you find some leafminers, squash them.

Monday, September 29, 2014

Avocado - First Flowers and Fruit

Fig.1  Indeterminate inflorescence

At the time when I was about to give up hope of ever making homegrown-homemade guacamole, our avocado tree bloomed this year - hope has dawned.  This is the same avocado tree  that I wrote about earlier. Like all other trees in my garden I expected this avocado to bloom sometime; but because it took almost nine years before the first flowers appeared, I was surprised to see panicles (clusters of flowers in one stalk) of flowers last spring.  I guess this is the thrill of growing fruit trees from seed. 

There are two types of avocado inflorescences (flowers) - determinate or indeterminate. Indeterminate inflorescence, terminates below a vegetative bud (Fig. 1), which according to the UC-ANR, is more common in this area.  In the case of determinate inflorescence, flowers appear at the terminal end of the flower-bearing shoot.  Avocado inflorescence develops in panicles of up to hundreds of flowers.  For the tree in my garden, there were very few flowers per panicle - which is not surprising since this is only its first blooming year. Maybe the second year will be better.  

Fig. 2   Cobweb-covered panicle.

After flowers, the next thing to look for are fruits.  There was one fruit that developed. The one and only (Fig.3).  Why?  Pollination is the major determinants of productivity.  Flowers have to be pollinated prior to fertilization and fruit setting - usually, insects play a huge role in this process. Close-up picture of the flowers on Fig. 2, gives an explanation to the singular fruit (Fig. 3) on the entire tree.   The flowers were covered with cobweb prior to anthesis (period when flower is fully open and functional). Any insect attempting to visit the flowers is in for a deadly trap.  Regardless of the complexity of the avocado pollination process, this situation alone seems enough to abort pollination.

Fig. 3    The one fruit.

Lessons learned:  
1.  Under local conditions, avocado takes nine years from seed to flower.
2.  Fruiting can happen in this area.
3.  A second tree is not a requirement to pollination.
4.  Spiders can hinder pollination.  :)

Friday, September 12, 2014

Re-potting and Dividing Cymbidium - Again

Fig. 1  Cymbidium:  Winter of 2014

Three years ago I repotted my cymbidiums into three gallon containers.  This year (late spring) I divided them again after they all finished blooming; turning each plant into three individual plants. In some cases I hesitated to divide them because I like seeing multitudes of spikes (instead of two or three per plant) shooting from among the sword-like sheaths of green leaves, so I repotted them into larger containers.  One of them now resides in a fifteen gallon container.  It will be interesting to see how it will perform next blooming season.

Fig. 2   Cymbidium in  a 10-gallon container.

2010 Potting Medium
Motivated by the high cost of bagged orchid mix, I thought of making my own mix for my cymbidiums as follows:
Decomposed redwood bark (.25 - 0.5 inch)
Handful of  potting soil

I used three years ago worked.  The plants did well - with lots of blooms and good root system.  The bark decomposed into very fine compost which I scattered along the rows of boxwood near my vegetable garden.

2014 Potting Medium
This year I used yet a different mix:  

Bark (0.5 - 1.0 inches)
Peat moss
Garden soil

With the current drought that we are experiencing, the peat moss would help retain more water allowing for less frequent watering.  Larger-size bark was used to allow good air movement around the root area.

Fig. 3  Cymbidiums lined up along south-facing wall.

Fig. 4  Newly repotted orchids.

Fig. 5    Pink cymbidiums:  Winter 2014

Fig. 6    Yellow cymbidiums

Right now, my orchids are doing well in their new growing media but it took them a while to get used to their new root environment.  I will be posing a new update come fall.

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