By Andrew Cawthorne and Jack Kimball

NAIVASHA, Kenya (Reuters) - A rubbish-strewn alley in a slum on the edge of Lake Naivasha in Kenya's Rift Valley leads to the cramped block where Julie Masete lives.

The 26-year-old flower worker spends her days in a nearby field, surrounded by tens of thousands of roses blossoming just in time for the global Valentine's Day market.

Masete points to black spots on her feet and says the pesticides and fertilisers used at the flower farm she works on give her rashes two or three times a month.

She speaks demurely about the frequent sexual abuse women face on the farms, sometimes by their supervisors.

"A friend of mine was abused," she whispered, lowering her eyes and avoiding eye contact. "Normally, people don't report it to the supervisor, because maybe you'll lose your job."

Masete is one of 50,000 flower farm workers in Kenya, one of the world's largest exporters of fresh-cut blooms.

The industry's success rings hollow for many workers, some of whom make only a dollar a day.

Sher worker Daniel Sagwe, who earns 4,700 Kenyan shillings (37 pounds) a month plus a 1,000 shilling housing allowance, said he could barely afford to buy water for his three children and wife.

The irony is not lost on him as every day he watches huge quantities of water being pumped out to grow the perfect rose.