Just a couple of questions: We have a large Meyer lemon tree in our backyard that has been very productive over the past few years. But this year, a lot of the fruit have rather large unsightly knots on the surfaces. What causes this and is there anything that we can do for it?
The condition you are describing is most likely a fungus infection called citrus scab, common in high rainfall areas.
The disease is often described as light brown, raised, warty scabs appearing on young stems, leaves and fruit. Spores are produced within these scabs and will spread to other tissues by the splashing rain or irrigation water. Citrus scab can reduce yield and the quality of the fruit. For home production, however, the fruit will still be sweet and juicy. In worse case scenarios, a copper fungicide may be applied. Highly susceptible citrus include Fremont, Clementine, Murcott and Frost Satsuma mandarins; Orland Tangelo; Tahitian lime and Rangpur lime. Immune citrus are as follows: sweet orange, navel orange, pummelo and grapefruit. See www.gardenguyhawaii.com for the complete article on citrus scab.
I don’t think your column on the African snail mentioned anything about killing them with salt. Can that be used as well? Mahalo, Teri
I neglected to mention salt, because slugs and snails are not fast-moving and can easily be scooped up and discarded, that is, if you’re not using baits. Now if you don’t want to handle them, then apply salt or other home remedies. Salt kills slugs and snails by dehydration. It is obviously easier to kill slugs than snails since the slugs have no protective housing. The one disadvantage to salt (sodium chloride) is that sodium is not good for the soil. Yet in small amounts and with ample rain, it should not be a problem.
Another home remedy is to spray these pests with a 4:1 solution of household ammonia. This works well and will break down into available nitrogen for the plants.
FYI: Here in Puna, the main issue with asparagus is maintaining a high pH while also fertilizing. They like lots of nitrogen which lowers the pH. I have had good luck with a foliar spray of potassium nitrate in roughly a 2 percent solution. Almost monthly applications of Dolomite helps. Mulching is very important to keep the plants happy and the weeds down. Aloha, Carol
The ideal pH range for asparagus is between 6.7 and 7.5. They do not grow well at a pH much less than 6. For this reason, adding lime before planting is recommended. The additional applications of lime, once the plants are in the ground, are also beneficial. Your point of fertilizing with a material which would maintain a higher pH (closer to 7 than to 5) is a good one.
Most nitrogen fertilizers are acid forming, meaning that, over time they will lower the soil pH, or at least, help maintain a low soil pH. Consequently, it would be wise to apply a fertilizer which will help raise the pH of the soil, thus help make it more alkaline. Soil applied potassium nitrate is a good fertilizer for this purpose. Calcium nitrate and sodium nitrate fertilizers are also good for raising the soils pH. In contrast, ammonium and urea fertilizers lower soil pH, making it more acidic. Triple 16 is made with ammonium and urea and is, therefore, acid forming.
Master Gardener Classes
The University of Hawaii Master Gardener Program will start a new 2013 class in February.
The Master Gardener Program trains individuals in science based gardening. Upon completion of the program, trainees volunteer to work on community projects and to help home gardeners with their gardening questions.
Classes will be held in Hilo from 9 a.m.-12 p.m. Tuesdays and Thursdays, Feb. 26-April 11. There is a class fee of $105. Application deadline is Dec. 15.
Contact Andrew Kawabata at 969-8251 or email him firstname.lastname@example.org.
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 email@example.com.