Now Is The Time

By eunice Messner

CHERIMOYA

The highlight of the winter months is the enjoyment of cherimoya fruits. I still have a few left on my ‘Pierce' and ‘Elixir' trees. It will probably be April before I bring in ‘Elixir' scion wood. There is no sign

of their brief dormancy period yet. If it is possible to reach those tall limbs, I will strip the leaves off a couple of weeks ahead of time before pruning.

Ideally, I have found it best for the seedling rootstocks to be ½" to 3/4" in diameter and for them to be in the 4"x14", or larger, tree pots. I grafted 20 smaller size last year and 19 of the 20 showed signs of new growth, but they remained in a comatose state, even though the grafts took. They never grew further and some died. I had read applying rooting hormones to the scion would be beneficial; well it sure didn't work. So, I hope others had better luck then I and will have some grafted plants for the Green Scene.

E-MAIL CONVERSATIONS WITH A MYCORRHIZAE EXPERT

I thought you might like to "eavesdrop" on my email correspondence withDr. T.V. St.John. I first read one of his articles in our 1985 Yearbook and he has been kind enough to respond to my recent questions regarding inoculating legumes and other related questions.

Eunice: I am trying to clarify whether mycorrhizae may be used as an inoculant in lieu of Rhizobium bacteria on peas and beans. My experience was that it just served as an enhacer.

Dr. St.John: Mycorrhizal inoculum is not a substitute for Rhizobium. They involve different organisms, a different type of symbiosis, and assist with different nutrients.

Rhizobiums are nitrogen fixers. They transform atmospheric N to amino acids, which the plant takes up. Mycorrhizal fungi extend from the root out into the soil and aid in extraction of phosphorus. They do not "create" P, in the way that Rhizobium almost create N, but, because mycorrhizal fungi are better than the unaided plant at finding this P.

Mycorrhizal plants react as though fertilized with phosphorus. If your soil is low in P (and has no native mycorrhizal fungi) the Rhizobium may not be able to do their job, even if you add them. This is because N fixation demands lots of P. Sometimes it takes both inoculants to see the growth response. If your soil has been growing legumes for several years you may not need to reinoculate.

Eunice: It is my understanding that when you till the soil it becomes more bacteria oriented -- which is okay for vegetables -- but not for fungal oriented fruit trees. What happens to the mycorrhizae when you till the soil?

Dr. St.John What happens is you break up the mycorrhizal network. That weakens some of the ropagules. Before tilling the mycorrhizal fungi were concentrated near the surface. After tilling some are deep, some are exposed (and will die) and some are back where they started. This would also tend to lower inoculum potential.

On the other hand, that does not seem to set things back more than a few weeks if other things are right. Tilling has some well known good points, so this is a kind of a trade-off. You can till or even fumigate (heaven forbid!) Based on info from commercial growers in the Imperial Valley, the native mycorrhizal fungi move back from deeper soil if the kill was not too deep.

Eunice For organic growers, is bacteria oriented soil sufficient for growing vegetables or would added mycorrhizae be of some benefit?

Dr.St.John For most crops (but not crucifers, beets, chard, spinach or amaranths) mycorrhizal fungi are an advantage. However, unless you have done something rather drastic, organic gardeners already have mycorrhizae. The only exceptions would be the first planting on newly graded ground (a new housing tract) or maybe the first planting after very thorough solarization. In general, solarization is a good thing. It so decreases the bad bugs and invigorates the good bacteria that mycorrhizaal fungi seem to burst back up, greatly invigorated from below the kill zone.

Eunice Does a well-made compost contain all of the microorganisms in what is called the "Soil Food Web"/ (Actinomycetes, yeasts, bacteria, mycorrhizaae, etc)

Dr. St.John Ordinary compost would not contain mycorrhizal fungi. They are sensitive to heat and some of the first to be killed by composting, if the materials even had any mychorrhizal fungi to begin with. There would only be mycorrhizal fungi in the compost if you scooped up some underlying soil with the compost, or if live plant roots grew in it for several months after it was finished.

APES PREFER ORGANIC

Monkeys at Copenhagen Zoo are going ape over organic bananas and other fruits, rejecting non-organic foods left in their cages. Copenhagen Zoo, which hopes to be awarded a "green label" as an

environmental zoo, began last year feeding its animals at least 10 percent organic products. Zoo Keepers said, "The tapirs and chimpanzees are choosing organically grown bananas over the others. The chimpanzees are able to tell the difference between the organic and the regular fruit. If we give them organic and traditional bananas, they systematically choose the organic bananas, which they eat with the skin on. But they peel the traditional bananas before eating them." Unfortunately, we humans have to rely upon labeling to distinguish the good products.