WYNONNA JUDD and her sister ASHLEY are locked in a nasty custody battle over the country star’s teenage daughter!

In a blockbuster exclusive, The ENQUIRER has learned Wynonna, 49, recently lost custody of daughter Grace, 17, to Ashley, and sources say the redheaded singer has been on a rampage ever since.

“Kiss the Girls” star Ashley has even accused Wynonna of hiring a private eye to attach a tracking de­vice to her Mini Cooper – a vehicle that Grace often drives – so she can gather evidence to legally reclaim her daughter, the sources add.

“Wynonna is furious that Ash­ley has poked her nose where it doesn’t belong!” an insider told The ENQUIRER. “She says that Ashley has ‘stolen’ her daughter, and Wynonna is spying on Grace because she wants her back home.”

Grace and her mother have been at odds for years, with Grace disap­pearing for several days during a flight layover in spring 2011 while re­turning home from boarding school.

The two also have clashed when Wynonna – who wed drummer Cac­tus Moser in June 2012 – sent Grace to a “behavioral” camp in December 2012 for six months, according to the sources. Grace apparently became so desperate to escape her mother’s verbal abuse, pill-popping and booz­ing that she petitioned a Tennessee court to grant temporary custody to her aunt Ashley.

“Legally, Grace couldn’t move out of her mother’s home without per­mission,” a source disclosed. “So she went to her aunt Ashley and asked for help. After Grace described her mother’s nasty name-calling, put-downs and substance abuse, a judge agreed to give Ashley temporary cus­tody.”

One of Wynonna’s representatives said the information regarding the verbal abuse, pill popping and booz­ing as well as the custody battle was not accurate, but since the judge awarded temporary custody, sources say Grace has lived at 45-year-old Ashley’s home. The house sits on a sprawling piece of property adjacent to Wynonna’s spread in Franklin, Tenn.

She drives Ashley’s silver Mini Cooper, and in early November, a wireless GPS tracking device was found on the car when Grace took it to a muffler repair shop, according to the Franklin Police Department.

Cops tracked the device to a private detective in Nashville, who refused to comment. But Wynonna’s attor­ney later admitted to cops that the singer got the device from the pri­vate detective and gave it to Grace’s father, Wynonna’s ex-husband Arch Kelley. The attorney claims that Kel­ley placed the device on Ashley’s car, but Kelley has denied knowing anything about it.

“Ashley’s convinced that Wynonna put the GPS on the car Grace uses because she’s furious over her close relationship with the girl,” said a Judd family insider.

The source added: “Ashley, Wynon­na and their mother Naomi have had a difficult relationship for years.

“Ashley knew going to court was only going to add fuel to the fire, but she had to help Grace get out of her mother’s house.”