Irrigation schedules were evaluated on `Cresthaven' to determine if water could be conserved without reducing fruit size or yield. Tensiometers were used to schedule trickle irrigation in 1984-88. Treatments were no irrigation or irrigation when soil matric potential reached 40 or 60 KPa 30 cm deep. When production began in 1986, trees were either irrigated until Oct. or until after harvest (1-7 Aug.). In 1989, class A pan evaporation was used to schedule irrigation by replacing 100% evaporation. Trees were irrigated from bud break to harvest or Oct., beginning at stage III fruit growth to harvest or Oct., or not irrigated. The irrigation treatments were in factorial combination with an annual ryegrass ground cover or herbicidestrip. The ryegrass was seeded in Oct., then killed at the onset of stage III fruit growth. Water application was reduced 50% when irrigation was discontinued after harvest compared to irrigation until Oct. Non-irrigated trees had smaller trunks than irrigated trees; however, there were no differences in trunk size among irrigation treatments. Non-irrigated trees yielded less total fruit and fruit over 7-cm diameter than trees irrigated until Oct., but there were no significant differences in yield among irrigated trees. Flower bud density or fruit set was not affected by treatment. The orchard floor management did not affect tree growth or yield.
Susan M. Huslig and Michael W. Smith
Susan M. Huslig, Michael W. Smith, and Gerald H. Brusewitz
Irrigation schedules were evaluated on `Cresthaven' peach [Prunus persica (L.) Batsch.] to determine if water application could he reduced or omitted without affecting fruit size or yield. Tensiometers were used to schedule trickle irrigation during 1984-M. Treatments were no irrigation or irrigation when soil pressure potential at a 30-cm depth reached 40 or 60 kPa, respectively. When production began in 1986, trees were either irrigated until harvest (1-7 Aug.) or until October. Beginning in 1989, class A pan evaporation was used to schedule irrigation by replacing 60% of evaporation. Trees were irrigated from budbreak to harvest or October, from beginning of stage III fruit growth until harvest or October, or trees were not irrigated. The irrigation treatments were in factorial combination using sod middles, with annual ryegrass (Lolium multiforum Lam.) seeded under the trees or a sod-herbicide strip. The ryegrass was seeded in October, then killed at the onset of stage III fruit growth. Water application was reduced 32% to 57% when irrigation was discontinued after harvest compared to irrigation until October. Irrigation before stage III fruit growth did not affect fruit yield, size, or pruning weights compared to trees irrigated at the onset of stage III fruit growth. Trunk size was increased by irrigation; however, there were no differences in trunk size among irrigation treatments. Irrigation occasionally increased fruit size and yield compared to no irrigation. There were few differences in flower bud density, fruit set, yield, or fruit size among trees with reduced irrigation schedules compared to trees receiving irrigation from budbreak until October. Annual ryegrass decreased shoot growth in 1990 and flower bud density in 1991; however, fruit set was not affected. Annual ryegrass depleted excess soil moisture during the spring in some years, then conserved soil moisture after it was killed. Using sod with annual ryegrass under the trees may be a viable alternative to management with sodherbicide strips.
William Reid, Susan M. Huslig, Michael W. Smith, Niels O. Maness, and Julia M. Whitworth
The optimum time for removing pecans [Carya illinoinensis (Wangenh.) K. Koch] to enhance return bloom was determined. Fruit were removed from part of `Mohawk', `Giles', and `Gormely' trees five times during the season as determined by fruit phonological age: immediately after postpollination drop, at 50% ovule expansion, at 100% ovule expansion or water stage, during the onset of dough stage, and 2 weeks after dough stage. Return bloom of all cultivars was increased by fruit removal during ovule expansion. Removing `Mohawk' and `Giles' fruit shortly after pollination induced the greatest return bloom. Return bloom in the small-fruited `Gormely' was equally stimulated by fruit removal at any time during ovule expansion, a result indicating that early fruit removal may be more important for large-than for small-fruited cultivars. If a commercially feasible method to thin pecans is developed, our studies indicate that the optimum time for fruit thinning would be during ovule expansion.