The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) recently issued an article, Science‑Based Plant Defense So Your Crops Perform Better. The authors are multi-county citrus Extension agent Edwin Gutierrez-Rodriguez and Jonael Bosques-Mendez, a county Extension director. Edited excerpts follow:
ROOTS AND WATER
Plant roots are strategic. They possess the structure and ability to alter their growth patterns.
When the soil surface starts to dry out, but moisture remains deep down, roots receive a hormonal signal to grow deeper, chasing water reserves.
Conversely, roots are also smart about growing sideways. They will actively form more branch roots in moist soil pockets while avoiding growth in dry patches. This architecture is orchestrated by several plant hormones, such as auxins and abscisic acid. Plant hormones may act as messengers, traveling from the leaves and shoot tips down to the roots, telling them where to grow. One of the priorities in HLB management at earlier stages should be to maintain this hormonal balance.
Water in the soil, availability, frequency, wet bulb temperature, time and other factors provide different information to plants. We can’t truly know what’s happening in the root zone without measuring.
While many tools exist, the key is to move from guessing to data-based decision-making. For crops like citrus, science has shown that sensors using time domain reflectometry or time domain transmissometry technology can be more effective at providing accurate soil-moisture information.
For example, a healthy, mature citrus tree on deep, sandy soil can have roots extending 5 feet deep, far beyond what can be seen on the surface
SUNLIGHT
What sunlight does for plants is far beyond photosynthesis. Although it is poorly discussed in the context of disease management, it has long been explored for its role in plant defense.
In plain language: Sunlight + oxygen + certain natural compounds = damage to pathogens.
On the insect management side, some plant compounds have been proven to be sunlight‑activated pest killers with high potential.
TAKE-HOME MESSAGES
- Soil moisture sensors help to decide when to irrigate, how long to run the system and where it is needed.
- Proper irrigation keeps oxygen in the root zone and prevents trees from reaching the permanent wilting point, which causes lasting damage.
- Place irrigation emitters to wet the active root zone, not the trunk. This prevents stunting, encourages strong root growth and improves water-use efficiency.
- Prune when necessary by removing twisted, overcrossed, sick or dead branches.
- Optimize light penetration into the canopy based on your crop, tree age and other factors.
- Consult with your local Extension Agent.
- A well‑managed irrigation program:
- Reduces air bubbles in the tree’s sap flow
- Minimizes nutrient loss from leaching
- Supports steady photosynthesis for healthy growth and yields
Source: UF/IFAS
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