Have a gardening question? Call the Master Gardener Helpline Monday - Friday 9:00 a.m. - noon (559) 456-7564 Or visit the UC Cooperative Extension office and ask for a Master Gardener. If you have questions about a specific plant or insect, it helps if you bring a sample with you. UC Extension Office: 1720 S. Maple Ave. Near the Fresno Fairgrounds, just south of Butler Ave.