As temperatures warm up, it is the right time to water and fertilize longan to promote flower bud emergence
The main task in longan cultivation at present is to promote timely flower bud emergence in the trees. Attention should be paid to weather changes, frost damage prevention, and thorough orchard cleanup to reduce the occurrence of pests and diseases.
At present, according to the author's observations in lychee and longan orchards in Guangzhou, trees of the early-maturing variety Sanyuehong that had early shoot control have flower clusters over 10 cm long, while trees with late shoots show no flower buds yet; trees of the variety Feizixiao that had early shoot control have flower clusters nearly 10 cm long, while buds on trees with late autumn shoots have not yet sprouted; trees of the varieties Nuomici, Guiwei and Huaizhi that had early shoot control have flower clusters 2-3 cm long, while buds on trees with late autumn shoots have not yet sprouted. For autumn shoots that emerged in early to mid-October last year, under the recent warming temperatures, most have already shown "white dots." Young longan trees began sprouting as early as January when temperatures were relatively high, and stopped growing after temperatures dropped; after "Lichun" (Start of Spring), the buds began to soften and started sprouting again; vigorous mature or old trees with timely autumn shoots have buds that have already softened and are preparing to sprout; trees whose autumn shoots matured slightly late have not yet sprouted.
Recently, with warming temperatures and dew, as long as lychee and longan are growing normally, their buds will sprout one after another, sending out flower clusters or new shoots; the main task at present is to ensure timely flower bud emergence in lychee and longan, pay attention to weather changes, prevent frost damage, do a good job of orchard cleanup, and reduce the occurrence of pests and diseases.
Longan is currently in the late stage of flower bud differentiation, the flower bud emergence stage, or the flower cluster sprouting stage. On Hainan Island and in western Guangdong, "sprout flushing" occurred during the high temperatures in January; at present, flower clusters in many orchards are growing normally, and timely autumn shoots can all emerge as normal flower buds.
> Currentlongan cultivationmanagement key points:
(1) Fertilization.Many orchards, because of excessive fruiting, see a decline in the economic value of the fruit, and the trees also become weakened, showing alternate bearing. Therefore, fertilization and soil improvement are needed. In addition to providing nutrients, organic fertilizer can also cultivate microorganisms around the soil and has a good effect on soil water and air retention. Fertilizing at the flower bud emergence stage not only provides nutrients for flower cluster sprouting, but also provides nutrients for flowering, fruit set, and the early growth and development of young fruit, so quick-acting fertilizer should be mixed with slow-release fertilizer. Generally, compound fertilizer is mixed with organic fertilizer; if the trees are somewhat weak or the leaves are yellowing, an appropriate amount of quick-acting nitrogen fertilizer can be added.
(2) Watering to promote flower cluster sprouting.For longan to emerge flower buds normally, in addition to sufficient nutrients, appropriate climatic conditions are also needed, such as a temperature of 10-13°C, intermittent light rain, and sunshine; under such conditions there will basically be no "sprout flushing." After "Lichun" (Start of Spring), temperatures rise relatively quickly, especially when hot and rainy weather occurs, making "sprout flushing" very likely. At present, trees that have not yet sprouted should be given one thorough watering, and the canopy should be sprayed 1-2 times with Qingyise cytokinin, to strive to have longan emerge flower buds on schedule.
(3) Orchard cleanup and pest and disease control.Through orchard cleanup, pest and disease damage is reduced. The main pest harming longan in spring is the longan psyllid, which damages the new leaves of longan. When temperatures are relatively high, overwintering stink bugs begin to become active and can be caught by hand or killed by spraying 800-1000 times diluted Baidichong solution.
(4) Prevent "sprout flushing" to ensure flower quality.If "sprout flushing" occurs, when the first new leaf unfolds, spray once with Kongshaoling (shoot-control agent) to force the leaves to stop growing or to harden or turn green, allowing the flower clusters to grow. When the new shoot leaves droop, yellow, and shrivel, it indicates that the leaves have stopped growing and no treatment is needed.