It may be OK for Robusta, but

not for cocoa, he says

Gliricidia maculata, recommended by Don Barrett as a satisfactory shade for Robusta coffee, is a most unsatisfactory shade for cocoa in New Guinea, according to New Ireland planter Jim Grose.

HE found it very easy to establish but very hard to get rid of. It was not susceptible to hormone weedkillers.

Mr. Grose, who has 200,000 cocoa trees, mostly under coconuts, in Poliamba Estates, New Ireland, of which he is managing partner, tried gliricidia on a 25 acre block of cocoa.

“We put it in because we were attracted by the fact that it was easy to establish,” he said. “But probably due to its rampant rooting system it seemed to be detrimental to cocoa, which didn’t bear even with the shade severely thinned.

“After 10 years we pulled it all out and planted leucena glauca.”

Mr. Grose feels planters could control gliricidia with constant prun ing and a lot of labour, plus plenty of intelligence to see that thinning is done carefully (otherwise you end with too much shade or not enough).

“Perhaps on a small block of cocoa

you can do this,” he said. “But when you have, say, 500 acres the less work you do the cheaper you produce your cocoa.”

Rubber, too

Poliamba Estates have been putting more and more rubber under cultiva tion recently. They currently have 400 acres and in another two years plan to have 700, The oldest rubber on the plantations is one year in the ground.

The planting is a high yielding variety—and needs to be, according to Mr. Grose.

“Rubber prices have been falling steadily, so low-yielding varieties, or any inefficiencies on the plantation could be disastrous,” he said.

Oldest rubber on New Ireland is on Ross Irvine’s Libba plantation, which should be tapped in two years.

There are 200 acres on Libba.