Racing at Charles Town Turf Club has been canceled tonight and Thursday, with Virginia segment of the Horsemen's Benevolent and Protective Association having begun a boycott to protest the state legislature's failure to grant the horsemen tax relief.

Don Hudson, track acting assistant general manager, said he hopes to have a full racing card Friday.

Hudson said the racing secretary at Charles Town would be contacting farms and stables in a effort to find enough horses to race Friday. "It's questionable whether we will be successful, but we're to try," Hudson said.

It was unclear yesterday how long the boycott would continue, but a similar boycott by horsemen at Waterford Park in Chester, W.Va., is expected to last at least until the end of the month, it was reported.

Rodney Peters, Charles Town representative of the HBPA, said the boycott was voted overwhelmingly after the legislature rejected the association's request for a reduction in the state's share of wagers at the track.

The state gets 5.75 percent of the money bet. The horsemen have asked that this be reduced to 3 percent October through March and to 4 percent from April through September, with the difference to be divided between horsemen and the track.

HBPA representative Fendall Clagett said the purse structure in West Virginia has decreased from $6.5 million in 1977 to $4.8 million last year.