2021–2022 Florida Citrus Production Guide: Canopy Management

There were no changes in recommendation from the 2020–2021 edition.

Tree Canopy Management Affects Dynamics of Herbaceous Vegetation and Soil Moisture in Silvopasture Systems Using Arboreal Legumes

Understanding ecological interactions between the arboreal and the herbaceous components is key to get the full benefits from silvopastoral systems. The objective of this 2-yr research was to evaluate productivity and nutritive value of signalgrass (Urochloa decumbens (Stapf.) R. Webster) subjected to shading from the tree legumes Gliricidia (Gliricidia sepium (Jacq.) Steud) or Mimosa (Mimosa caesalpiniifolia Benth.) under different tree canopy management. Trees were planted in double rows and were either unharvested or harvested only one row, leaving the other row unharvested. Response variables for the herbaceous vegetation included canopy height, herbage mass (green leaf blade, green stem, senescent leaves, and senescent stem), herbage accumulation rate, canopy bulk density, and soil moisture. Total herbage mass, green herbage mass, and green leaf mass were affected by treatment × month and harvest management × month interactions. Herbage accumulation rate in Gliricidia was greater (55 kg DM ha−1d−1) than Mimosa (32 kg DM ha−1d−1). Soil moisture was lesser at the Mimosa sites (16.2%) compared with the Gliricidia ones (17.2%), and it was greater between tree rows (21.9%) compared with full sun (11.5%), varying across the season. Harvesting management had a short-term transient effect on herbage responses. Tree canopy management can affect forage quantity and quality; however, these effects are transient and vary with tree spacing. Signalgrass grew faster and had better nutritive value when growing with Gliricidia.

Understanding climate and non-climate decision triggers to minimize Spring rainfall risks in vineyards

<p>Climate services have travelled a long way, however, the last mile still has to be covered until climate information can be appropriately integrated in the users’ decision making processes. When is the signal offered by a seasonal forecast useful? How and when can forecasts influence users’ choices? How does the use of the forecasts compare with the methods currently in place? The answer can vary across users and even across decisions that the same user may take.</p><p>This work analyses these questions through the decision making process of a wine producer aiming at reducing its exposure to spring rain variability. Spring rain drives risks of fungal disease causing crop loss and increased costs related to plant protection and canopy management. A transdisciplinary approach, including experts from various disciplines and the end user, is used to understand how and when a particular wine producer needs to trigger a decision linked to total Spring rainfall in order to reduce the risk entailed for plant protection and canopy management. Based on close collaboration, we construct a payoff function and simulate the decision driven by the choice of different forecasted probability thresholds and the business-as-usual decision, and we finally compare them to the observation. This exercise is repeated over 23 years to try eliciting the optimal threshold.</p><p>The results show that the optimal decision to avoid climate risks is not always a feasible solution, demonstrating that climate is only one of the variables taken into account in the complex decision making context of a business. This highlights the importance of interpreting seasonal forecasts appropriately according to each user's context and understanding how this information will be integrated in the decision processes.  Finally, it calls attention to the importance of co-creation in climate services and the need for extending the collaboration process up to the delivery phase, the so-called last mile.</p><p> </p>

The Effect of Elicitors and Canopy Management in the Chemical Composition of Vitis vinifera Red Varieties in Warm and Hot Areas in Spain

Canopy management practices in vineyards, such as sprawling systems and shoot trimming, can change the accumulation of metabolites in grapes. The use of elicitors of biological origin on grapevines of Vitis vinifera red grape varieties may also modulate the chemical composition of the berries. These modifications are often observed in the accumulation of phenolic compounds, including pigments. Both technical approaches are alternatives involved in minimizing the effects of global climate change in warm areas. The increase of temperature related to climate change accelerates the accumulation of sugars, but produces unbalanced grapes. This work establishes the use of button sensors to monitor the climate changes occurring at grape cluster level. Together with climate monitoring, conventional instrumental analytical techniques are used to follow up the chemical composition and the phenolic fraction of grapes in four different production areas in Spain. The effect of either treatment seems variable and to be affected by external factors besides the treatment itself and the climate conditions. While there is a fine effect that correlates with the use of elicitors in varieties like Merlot and Tempranillo, there is minimal improvement observed in Tintilla de Rota. The total phenolic index increases were between 2.3% and 11.8% in the first two parcels. The same happened with the vineyard’s canopy management systems, with increased pigment accumulation and the total phenolic index rising (37.7% to 68.7%) after applying intense shoot trimming, or a variation in sugar concentrations when using sprawl conduction. This study aims to provide viticulturists and oenologists in particular, and farmers in general, with data on the field regarding the use of alternative sustainable practices in the cultivation of grapes. The techniques used involved 100% natural products without adjuvants. The benefits obtained from applying some of these practices would be to produce technically mature grapes despite climate changes, and the elaboration of more balanced wines.

Management of Citrus Tree Canopies for Fresh-Fruit Production

Canopy management is a useful tool to induce precocity and maintain high production of optimum-sized, high-quality fruit. The aim of this new 8-page publication of the UF/IFAS Department of Soil and Water Sciences is to provide growers with practical tools with which to manage their trees for maximum fresh-fruit yield, quality, and profitability. Written by Andrew Krajewski, Arnold Schumann, Tim Ebert, Chris Oswalt, Rhuanito S. Ferrarezi, and Laura Waldo.https://edis.ifas.ufl.edu/ss698