Malawi farmers battle crop-munching pests as output seen falling

* Dry spell exacerbating risk to crop output

* FEWS NET estimates 10 percent drop in 2017/18 crop

* Farmers turn to neem tree for cheaper pesticide

CHIKWAWA, Malawi, March 23 (Reuters) - A worsening pest infestation is threatening Malawi’s staple maize crop for the second year running, leaving farmers struggling to salvage crops already faltering due to drought.

The outbreak of crop-munching fall armyworms, a pest from Latin America that first threatened African crops late in 2016.

Impoverished Malawi is periodically hit by food shortages as it relies heavily on rain-fed agriculture and most of its maize is grown on small plots by subsistence farmers.

“The worm is not dying, but we have to keep spraying in the hope it may give up. Last year it was the same,” said 20-year-old Patricia Ntasa in Chikwawa, 77 km (48 miles) southeast of Malawi’s economic hub of Blantyre.

In the same field, Stoneck Njanji, 40, was worn out as he tried to kill the pest using spray. “We must spray once every week until maize matures. It’s hard labour,” he said.

Official estimates of the damage to maize by both the drought and armyworms are underway, the government has said. Last year, half of Malawi’s maize was infected by armyworms.

The Famine Early Warning Systems Network (FEWS NET), which issues alarms about food shortages, said in its February report that drought and the pest infestation will reduce maize harvests by 10 percent in the 2017/18 (October to April) season.

Malawi’s maize production in the 2016/17 farming season stood at 3.2 million tonnes.

“Like last year, we have to think about what to do to find food,” said Barton Mapepa, 50, another farmer. Mapepa said his family relied on sweet potatoes to supplement its food supply.

Malawi declared the armyworms a national disaster in December after discovering the pests had spread to 22 of Malawi’s 28 districts. In 2017, the pest infestation also affected Zambia, Zimbabwe and South Africa.

Lewis Lipenga, a crops protection officer in the Agriculture Ministry, the army worm had grown resistant to chemical pesticides since its arrival in Malawi, while high temperatures helped it multiply fast.

The Catholic Relief Services (CRS) charity is working with farmers on cheaper methods to tackle the worm, such as spraying pulp from the leaves of the neem tree or planting crops resistant to the worm, such as sweet potatoes.

“The best we can do is to try and control it, rather than expecting to eradicate it completely soon,” said Dane Fredenburg, a project director for agriculture at the CRS. (Writing by James Macharia Editing by Edmund Blair)