When NOT to Survey With Drones! (Macadamia Canopy Management)
Canopy Mapping & Mistakes You Need to Avoid
Macadamia canopy area statistics are one of the least exciting of the metrics. In my eyes, a close second to tree-counts on the “boring metrics” scale, BUT equally as underrated, and just as important.
No fancy multispectral or thermal sensors here folks…
But if there were only a handful of metrics I could use for Macadamia orchard monitoring and management, canopy area statistics would be among the top choices, no doubt about it!
When to avoid drone surveying for Macadamia canopy metrics
FLOWERING STAGE:
Late winter or spring it can often be a windy time of the year in several macadamia growing regions. This makes drone surveying complicated, and negatively impacts data quality simply due to wind induced canopy movement.Depending on the type of survey and sensors you are using, you might want to take advantage of other metrics as well. Thus, survey timing during flowering, may not be optimal. Multispectral or thermal sensors tend to provide you with false negatives or positives during this time of season. Bloom colours can skew multispectral data. And we definitely see elevated "stress" at this time of season. And as flowers transpire, thermal data is affected as well.
Unless you are doing a very specific type of survey, try to avoid the flowering stage. “Special case” surveys may be something like monitoring blossom densities or "full bloom" timing from the air. An exercise well suited to crops that flower before they go through vegetative bud-break, such as deciduous crops. For example pome-fruit (apples, pears, quinces) and stone-fruit (peaches, nectarines, cherries, almonds).PRE-HARVEST:
Basically, when trees are laden with nuts. Why this is not an ideal time to monitor canopies specifically is because the crop itself can pull branches downward. And when seen from the air, the tree canopy will likely be reported as larger than it really is. You will often see this on younger trees bearing their first “big” crop, where main branches are thinner and easily affected by the extra weight of the nuts. A good time for yield scouting (also covered in my book) but too late for canopy monitoring drone surveys. Surveying a little later (post harvest) or earlier (nut set) will provide you with much better data.DURING / AFTER PRUNING:
Oftentimes a mistake that can easily be made by the uninformed. A late-season survey conducted far too late. Why do some conduct surveys after post-harvest pruning? Because they either have the time (finally!) or they feel like they can better afford the spend on utilising drone tech (post-harvest cashflow). But this is simply due to poor survey planning, mostly driven by FOMO, or a lack of patience. Or a pushy salesman neglecting to keep the farmer's best interests at heart. Stick to your strategy; and only survey at the right times, and where you will be sure to get the best ROI on your spend.
Another reason why pruning time is not the best time to survey, is because you skew canopy variance statistics. If you want to monitor variance / canopy homogeneity - or to plan variable rate applications - you want to do that with a full un-pruned canopy. Without flowering. Without an excessive crop. All things "being equal" and growth phases as "balanced" across most of the orchards, as best possible.
Also, pruning brings about added stress (which is to be expected). And if conducting multispectral surveys at the same time as your canopy monitoring survey, you will definitely pick up elevated stress metrics. The multispectral info will provide false red-flags - and ones you won't want to waste your time worrying about.
The only time you would want to survey late in the season, after pruning, would be to monitor pruning effectiveness/accuracy itself. Are the orchard canopies homogenous? Did the pruning team get the trees down to the planned size, or structure? Where are the gaps, where do I have missing trees?
For intensive high-density plantings it can be difficult to identify individual trees. With some pruning this is often a lot easier. But remember, only relevant if surveys are looking into post-pruning status, or tree census concerns, and not canopy monitoring or variance management.
So to recap...
All these times deemed “not to survey” are nice-to-have timings.
If the expense and time spent surveying (as well as time spent analysing post-survey data) are not concerns for you, by all means conduct the extra surveys. But it’s not completely necessary.
Remember that with each additional survey, you get diminishing returns. Survey too often, and will feel inundated with data, and miss the big picture. Not only that, but you may struggle to find the time between surveys to action any interventions developed off the back of the previous survey results.
Conduct surveys early-season (after flowering) and post-harvest (before pruning) for the best data ROI. These are optimal times for that first drone survey. Utilising canopy metrics at the right time, for precise orchard management.
So when should you survey?
Your canopy monitoring surveys can be broken down into two important surveys:
The initial drone survey.
The follow-up surveys.
The initial survey provides a baseline scan as well as a real-time orchard status overview.
The survey should be timed after any flowering has stopped, or post-harvest before pruning. So that’s 2 best timings to note, and each will be more or less relevant depending on your goals. Any of these could be your initial survey, and follow-up surveys would be timed to match, a year later each year.
Early Season (nut-set / nut-drop)
Late Season (post-harvest)
If you are monitoring younger orchards not yet in production, aim to time surveys according to phenology charts depicting when they would likely be at nut set/nut-drop. For the Southern Hemisphere this is usually mid-October to mid-December.
The later survey option (post-harvest) offers less time for intervention in the same season which would affect yield, but will provide data that could be used to optimise for the next season’s yield or orchard management decisions.
Likewise, if your orchard is young, aim for the time of season you would expect to harvest in the future once the trees are in full production. In the Souther Hemisphere this is usually mid-February to well into June for later areas and cultivars.
Extra notes on survey timing…
Understandably, drone survey timing is challenging across larger operations. Especially as certain cultivars have differing flowering starts and ends. ie) early varieties versus late varieties.
However, there should be a time in the season where most (if not all) cultivars on-farm are in the same phenological stage. This is how you want to time your surveys, either all cultivars at nut set, or all cultivars post harvest (before any pruning).
Being flexible by a week or two is also important as well. You will probably need to take the weather into account, and that flexibility helps. Keep it in mind.
Note, these are canopy monitoring and management drone surveys. For multispectral surveys, or surveys aimed at monitoring stress levels, water use, or all of the before mentioned, remember to take into account leaf flush and root flush timings to get the most from your surveys. I cover all these factors and timing considerations in my upcoming book on drone surveying for macadamia farming.
More about follow-up surveys…
In terms of canopy area it's imperative to obtain a real-time status (initial survey) as well as monitor changes (those that follow).
The follow-up canopy-growth monitoring surveys are important too, and perhaps even more so, once you have that baseline survey in the bag. The value of drone surveys imply compounds over time, especially when conducting year-on-year surveys.
While the first survey provides a large base of information, the follow-on survey adds new value. Farmers get an updated "real time" homogeneity snapshot and surveys can be compared to gauge orchard management effectiveness. ie. How well did your work in-field this past season turn into the results you planned for?
Simply put, the follow-on survey offers a comparison. And if the first survey was a benchmark, the second is what you’d measure against it.
The third against the first two combined, etc.
In this way, an average benchmark norm is created as well.
With ongoing effort, the “norm” is steered into the direction of your ideal outcome.
Ideal outcomes are achieved through acting on the data. It’s a cycle.
This journey to perfection represents measurable progress.
Even better… Progress pairs perfectly with sustainability frameworks, resilience, reducing input costs, self-reliance, risk mitigation strategies, and all that good stuff.
Comparisons offer feedback on intervention effectiveness, and any canopy variance changes. Canopy growth monitoring is important where younger trees need to "fill out" vegetatively. And it’s important to keep tabs on these statistics ahead of new plantings coming into production (and finally paying for themselves!) as they move toward their potential to produce more and more nuts for years to come.
Follow-on surveys are also useful to gauge how trees have responded to pruning done in the past. Pruning for shape and structure. For that central leader, or light penetration, and the like. Not to mention identifying factors in-field limiting canopy growth and influencing nut quality and yield.
Follow on surveys also help in gauging fertiliser program or watering strategy effectiveness. Bio-stimulant use, the effects of tailored IPM strategies, where you need to work on soil health, address drainage issues, etc, and the list goes on.
With continued and consecutive drone surveys, year-on-year, data-backed canopy management pays for itself. The ROI comes from knowing orchards intimately with a view from above, and taking action both proactively and reactively as needed.
Empowered with actual canopy metrics, variance stats, and quantifiable areas of concern, it’s 100% possible and plausible to enhance your orchard canopy management strategies.
Exact areas (hectares / acres) or exact numbers of trees that require attention are easily obtained. Record keeping is immaculate. Canopy management action-plans are structured and well thought out. More proactive, and less reactive.
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🎓 If you’d like to learn more about drone flight timing, and some of the other drone data metrics used in precision macadamia farming, consider enrolling into one of my free email short-courses.