(Sharecast News) - Agricultural products provider Plant Health Care expects revenues from its current year to be "materially below" expectations despite an "encouraging" launch of its new Harpin AB protein.PHC said the launch of its new Harpin AB product into corn crops alongside its major US partner had made a "very encouraging start", delivering sales of close to $1.5m.However, despite the strong launch, the AIM-listed firm agreed to delay the planned launch of Harpin AB into soy products, which holds a "comparable market potential", into 2019.PHC warned the delay, as well as prolonged droughts in South Africa which led it to restrict sales in the region until its inventory had been worked off, would result in revenues slipping "materially below market expectation".Looking forward, executive chairman Chris Richards said: "The shortfall in 2018 does not affect the board's confidence in the company becoming cash positive no later than 2020, within our existing cash reserves."As of 0920 GMT, PHC shares had tumbled 30% to 7p.