Monday, August 24, 2020

The Corn Earworm



The corn earworm is one of the most destructive insect pests of corn in the world. But here in Hawaii it is not quite as destructive thanks to CTAHR (University of Hawaii College of Tropical Agriculture and Human Resources) plant breeders. Hawaii-bred corn varieties are more resistant to the earworm due to their thicker and tighter husks, thus limiting the number of larvae that can gain entry to the ear. This allows growers to simply cut off the tips of the ears to remove any damage that may have occurred.

Most of the eggs of the corn earworm are laid on the young silks soon after the silks have emerged. Young larvae crawl down the silk to feed on the kernels, soft cobs and the silk itself.  Luckily they also eat each other, keeping populations low.

Corn planted early in the year is not as seriously affected as is late corn because population densities increase as the season progresses. Early plantings will have minimal damage; later in the year one or two worms may appear in the tops of each ear of corn.

Control
To help control the pest, between plantings destroy the crop residue or haul it off to the compost bin. This eliminates places that would harbor the pest. Several natural enemies are present in Hawaii and, in general, they keep the corn earworm at tolerable levels. In most cases, control is simply a matter of cutting off damaged ends of corn at harvest.

For those gardeners who are plagued with the corn earworm, here are some organic  pesticide recommendations from the University of California IPM program:
  • Spinosad -  must be applied on silks within 3 days after first silks appear and at 3-day intervals until silks turn brown.
  • Bacillus thuringiensis (Bt) -  may be dusted on silks every 3 days after 5 to 10% silk formation for partial control.
  • Applying a few drops of mineral oil with a medicine dropper to silks just inside each ear 3 to 5 days after silks first appear may be effective.

Friday, August 7, 2020

Pineapples - Easily Propagated





Can the top of the pineapple fruit be cut off and planted in order to produce a new plant? The answer is YES! There are many variations on how to propagate pineapple. The drier the environment, the more precise the instructions need to be followed. In Hawaii, especially in high rainfall areas, propagating pineapple is relatively easy. 
  


The simplest method is to cut off the top of the pineapple, called the crown, as you normally would do when cutting the fruit. Let the top sit in a shaded, dry area for 2-7 days. Before planting, remove the dried fruity portion and some of the lower leaves exposing  ½ -1 inch of the stem. Letting the crown sit for several days will seal the wound and make it less susceptible to rot. When planting, keep in mind that the mature plant can grow to 3-4 feet in diameter and height. Mature plants also have a tendency to fall over, thus planting several together, they will give each other support.

Alternatively, the stem can be placed in a shallow glass of water. Be careful to place only the stem and not the leaves in the water.  After a short time, roots will form; it is then ready to be planted outside.