Man­ag­ing the guava moth


Newly in­tro­duced gar­den pests are the bane of the home gar­dener. The guava moth first ap­peared in North­land in 1997, but MAF did not get in­volved till 1999.

By 2002 North­land or­chards were found to have some de­gree of in­fes­ta­tion, and since then com­mer­cial grow­ers and home gar­den­ers in other parts of the North Is­land and pos­si­bly some ar­eas of the South Is­land could have small, but grow­ing pop­u­la­tions of the pest.

When MFAT looked at Aus­tralia where the moth came from, it was re­ported as not be­ing a prob­lem in com­mer­cial or­chards, only as a home gar­den pest. The same was also said of the potato/ tomato psyl­lid, which has since be­come a ma­jor prob­lem here for com­mer­cial and home grow­ers. Be­cause the guava moth has nu­mer­ous host plants in­clud­ing citrus, lo­quat, plums, peaches, pears, ap­ples, macadamia, fei­joa and guava they are likely to find fruit to in­fest at any time of the year. There is a lack of real in­for- ma­tion about the moth. It would ap­pear that af­ter lay­ing eggs, pos­si­bly di­rectly on the tar­get fruit or nut crop, the cater­pil­lars hatch out in 10 - 15 days, and then eat their way into the fruit.

A spray of Wallys Su­per Neem Tree Oil mixed with Rain­gard (ef­fec­tive against codlin moth) should stop the cater­pil­lars from feed­ing. A re­peat spray over the fruit (no need to spray the whole tree) ev­ery 14 days till har­vest should be­gin elim­i­nat­ing the moths. Another fix is to wrap a branch in crop cover af­ter flow­er­ing is fin­ished to stop moths lay­ing eggs on its fruit.

Set up in­ex­pen­sive so­lar lights to at­tract the moths at night. Cover the lights with plas­tic wrap coated in cook­ing oil or petroleum jelly. The moths are at­tracted to the light and get stuck on the coat­ing. Dis­pose of them next day and reload the trap. Wallys Yel­low Sticky White-Fly traps could also be used in con­junc­tion with so­lar lights to hang on a pole at about the height of the low­est fruit­ing branch of the tree.

Re­mem­ber that lights on your prop­erty at night (in­clud­ing nearby street lights) act to at­tract moths and other noc­tur­nal pests.

On­line re­search in­di­cates that as most host fruit trees have a pe­riod of a few months from pol­li­na­tion to har­vest, it is likely that two or more gen­er­a­tions of moth will af­fect the same fruit tree. The grubs pu­pate over 14 days, in the top layer of soil and de­bris un­der the trees they have been feed­ing on. A gang of free rang­ing chick­ens would clean up any pu­pat­ing moths no prob­lem. No chick­ens? Try Neem Tree gran­ules. Sprin­kled un­der the trees th­ese work to con­fuse codlin moths when they emerge from their co­coons, and may do the same for guava moths if in­deed they find their host plants by smell. Other ideas pro­pose plant­ing aro­matic herbs or plants un­der the trees to con­fuse the moths, or us­ing a reg­u­lar olive oil and gar­lic spray pro­gramme.

Prob­lems ring me at 0800 466 464 (Palmer­ston North 357 0606) Email wal­lyjr@gar­de­

Web site gar­de­


Bug ex­pert Peter Peck­ham, shows the dis­tinc­tive mark­ings of a guava moth, another im­ported gar­den pest.

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