Growers of pineapple, a tropical fruit, face a number of unique challenges that producers of most temperate crops do not. A single pineapple plant crop production “cycle” requires on average 18-22 months from planting to harvest, with the crop planted and harvested weekly year round. Each variety has to be cultivated and managed differently. Plant growth regulators are critical in modern pineapple production for two reasons: to increase fruit size and to prevent natural differentiation of flowers or fruit (NDF), also called natural induction (NI).
RyzUp® (gibberellic acid, or GA3) is the PGR used in increasing fruit size, and is applied at two developmental periods, pre-force and post-force. During the pre-force period, RyzUp is used to promote vegetative growth and reduce cycle time. Even more critical is the post-force period, when RyzUp is applied to boost the development of the fruit. In this time period, RyzUp actually delays maturity by 7-10 days, but allows the fruit to continue to grow during this window. In fact, average fruit weight is increased by approximately 150 grams per fruit. These bigger fruit are worth more, generating higher returns per hectare. In addition, total tonnage harvested is greater, with research showing an additional 8-10 tons of fruit harvested per hectare in RyzUp-treated fields.
RyzUp is either broadcast applied or sprayed directly on the fruits early in the fruit-filling stages (at dry bloom stage and again seven to 14 days later).
A second PGR, PinCor® (aminoethoxyvinylglycine or AVG) is needed because pineapple plants’ ethylene production can cause NDF/NI at the wrong time. This physiological event, caused when the pineapple produces natural ethylene due to stress, leads to uneven sized fruit.
The most notable stress to trigger NDF is a drop in temperature, and a drop to just 18 degrees C is sufficient to cause a problem. Other stresses that can pose a threat include reduced or low photoperiod and/or solar irradiation, lower temperatures or cold events swinging to high day temperatures, low and/excessive events of soil-water relations, nutritional level issues, weight of plant (when correlated to age of plant), and planting seed types.
Broadcast or directed sprays of PinCor at the vegetative fruit stage and prior to NDF and/or artificial flower induction can prevent uneven harvest. Growers need to begin applications prior to the first incidence of NDF, and continue repeated applications at a 7-day frequency during the NDF susceptible period.