Aloha from Kahului, Maui! I planted the yellow lilikoi a couple of years ago and … it has been producing fruit. The lilikoi on the vine is my second crop. The vine is crawling on my chain-link fence, and soon it will reach the end of the fence. I was told to cut it back so it will bear more fruit. How do I do that? Do I trim the vine close to where the base root is? And when do I trim the vine? (I picked that last fruit in the first crop around January and the new crop of fruit is almost matured.)
Also, the vine has a very nasty inhabitant … a horny brown caterpillar that bites (so my neighbor said as I am deathly afraid of caterpillars and worms). How do I get rid of that caterpillar? — T.E.
To prune or not to prune is still up for debate. Older University of Hawaii publications state that it is undetermined whether passion fruit, or lilikoi, require regular, periodic pruning. Some experiments have shown that unpruned vines actually yield more than pruned vines. Many commercial orchards, however, are pruned for a variety of reasons: to facilitate insect and disease spray applications, to eliminate vine matting on the trellis, to keep vines off the ground, to make harvesting easier and generally, to keep vines within bounds. Some recommend pruning to maintain vigorous growth or to force new growth if needed.
It is evident that there is no hard and fast rule for pruning. If the vines lack vigor, then pruning would be appropriate. But if the vine is growing well, pruning may be unnecessary. I have an 8 year old vine which has not been pruned and is growing over tall waiwi (strawberry guava) trees. It is a vigorous vine and produces well. If pruning is exercised, prune after harvest, cutting back the vigorous growth about one third. Note that yellow lilikoi is more sensitive to pruning and will not tolerate severe pruning.
The caterpillars on the vine are probably the larvae of the passionvine butterfly, a beautiful orange butterfly with black markings. It is similar to the monarch and one of several migratory butterflies. The larvae are a combination of black, orange and white, depending on their stage, with conspicuous black spines. These caterpillars do not bite; the spines are rather soft and should cause no harm. But the caterpillar itself is poisonous if eaten. Although some birds will eat the caterpillar with no ill effect, others shy away. This caterpillar feeds exclusively on passion vines. They often occur in large numbers and can quickly defoliate a young or newly planted vine. Control measures may be needed. Once the plant becomes large with many leaves, the larvae usually do little damage. In addition, this pest often becomes highly parasitized which means it is under good biological control.
If you decide to spray, BT (Bacillus thuringiensis) would be a good selection. It is considered organic and does not harm humans.
Tip for the first time grower: For those with minimal space, grow crops that produce the maximum amount of food for the area.
Radishes, onions, lettuce and bok choy will all produce abundantly in a small space. Tomatoes will take up more room but will produce well for the space given. On the other hand, plants like pineapple, watermelon and pumpkin squash take up a large area for the amount of fruit produced. When planting a vegetable garden always visualize what the mature plant will look like. For more tips for the home gardener, see my website at www.gardenguyhawaii.com under the vegetable label.
Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years. Email your questions to Sakovich at firstname.lastname@example.org.