Mealybugs and Aphids on the Roots

Pineapple mealybug             

 There are species of aphids and mealybugs that attack the roots and the crown line of plants. Many times when plants are pulled out of the pot, whitish fuzzy bugs in the soil or on the roots can be seen; they are the root aphids or root mealybugs.

In Hawaii, the pineapple mealybug is common. The adult females are described as plump and convex in body shape and pinkish in body color. Primarily a pest of pineapple and other bromeliads, yet these mealybugs also attack banana, celery, citrus, cotton, coffee and hibiscus. Wherever pineapple is grown, the pest is present including all of the major Hawaiian Islands. Plants rarely die from a mealybug infestation.

Control of this pest depends on controlling the ants which provide the mealybugs shelter and protection from predators and parasites. Without ants, mealybug populations are small and are slow to invade new areas because of the presence of the many natural enemies (the good guys) that are in Hawaii.

In infested areas of the garden, after the crop is removed, the soil should be turned over and all crop residue removed including grassy weeds which may harbor the mealybugs.  Host plants of this pest (listed above) should not be grown in this bed for at least a year.

Avocados: Bountiful Blooms, Few Fruit

 Avocado, as well as citrus trees, produce an abundance of bloom. But only a fraction of those flowers remain to produce fruit. Furthermore, after the fruit is set, some premature fruit drop will occur; it is the natural thinning process.  

Yet any stress occurring during the time of bloom and young fruit development, will cause additional fruit drop.  These stresses include too much water, not enough water, nutrient deficiencies, vog (volcano emissions), and a few days of sudden high temperatures. Heavy rains during the bloom period can also contribute to low or no fruit set. Since pollination is principally by bees, a lack of them will also add to poor fruit set. 

In addition, avocado trees are categorized according to their flower type, either “A” type or “B” type flowers.  When only trees of the same flower type are planted together, they will produce fruit. However, when the opposite flower type is planted nearby, production is increased.  Having both flower types in a commercial orchard is important. In a neighborhood setting, a high probability exists that a tree with an opposite flower type will be in the area. Also note that avocados will produce a heavy set of fruit one year and usually rest the next by producing a lighter set.

If trees are a grafted variety, they should begin to produce in three to four years, while avocado seedlings (non-grafted) will take much longer to produce, perhaps seven to ten years.    

Soursop

Soursop, related to the cherimoya, is a mid-sized tree reaching about 25 feet tall. It is best propagated from seed which will germinate in 15-30 days. The fruit, which can weigh up to 10 or 15 lbs, is often used in making sherbets and other drinks.

The tree grows rapidly and begins to bear in 3 to 5 years. Unfortunately, a normal crop for young trees is only 12 to 24 fruit per tree. When producing fruit, this tree is particular about its environment.  It has been observed in tropical countries that soursop trees grown in very humid areas often grow well but bear only a few fruit, usually of poor quality. Most of their flowers and young fruit fall because of a fungus called anthracnose, which does exists in Hawai`i.  In Puerto Rico, the tree is said to prefer an altitude between 800 and 1,000 ft with moderate humidity.

Drought stress is another reason for fruit drop. Mulching is recommended to avoid drying of the shallow, fibrous root system during hot, dry weather. Dry conditions, rainy conditions and high humidity all contribute to poor production. In some areas of the world hand pollination is recommended. There may not be ample insects around to pollinate, and therefore, fruit production would be low.

Now for some humorous folklore: in Materia Medica of British Guiana, the cure for intoxication is “break soursop leaves in water, squeeze a couple of limes therein, get a drunken man and rub his head well with the leaves and water and give him a little of the water to drink and he gets as sober as a judge in no time."