Summer Plant Health Audit: What’s Affecting Your Landscape?
By Eduardo Beltran and Joe Feather
All plants need water/oxygen (root zone), C02 (leaf zone), healthy soil, and nutrients. If parts of the landscape are in decline, here are some potential reasons and remedies.
Main Reasons a Plant Dies
When a plant is dying or in decline, before replacing it determine the underlying issue.
- Too dry / too wet – This can be caused from the current irrigation plan missing an area, or from a drainage issue. Check during watering times for pooling water and dry areas.
- Planted too deep / too shallow – Excessive depth can cause stem suffocation. Not deep enough can cause root exposure (to elements, insects, etc.). Either will stress a plant to decline.
- Too much sun / too much shade – Summer days may offer more or less light than expected when the plant was planted. If discovered early enough, relocate the plant to another part of the landscape with correct exposure. Nursery plant tags (or gardening books) will say the amount of sun required for each plant, in terms of hours of sunlight. Remember morning sun is “gentler” than afternoon sun exposure.
- Too hot (summer) / too cold (winter) – Is the plant suitable for your planting zone? Using the US Department of Agriculture interactive map, you can determine the hardiness zone and heat zone specific to your area. Most nurseries list the hardiness zone on each individual plant tag.
- Chemical damage – Note if the plant appears burned, has desiccated leaves / stems, or curling of the leaves. These could be indicative of contact with herbicide spray (including spray drift from other areas), too much fertilizer, or from poor water quality.
- Mechanical damage (physical) – Be mindful of potential foot traffic, vehicle paths, construction damage such as digging around plant that may have affected the plant
If none of these appears to be the reason for the plant’s decline, look to the secondary level possibilities, outlined below.
Many times, insects keep the plant from thriving, as opposed to outright killing it. Insects such as aphids, scale, mites, and some caterpillars and beetles will multiply in a susceptible host, chewing on various plant parts. However, if allowed to increase to the point of depleting all the plant’s defenses – or if (like borers) they destroy the essential parts of the plant – the plant will not survive.
A majority of insects are seasonal, although a few will infest year-round if the climate is favorable. Some common, destructive insects in north and central Texas are aphids, spider mites, bagworms, tent caterpillars, chinch bugs, white fly, thrips, grubs, and tree borers.
Control can be chemical or cultural.
With chemical control, first pinpoint the specific insect causing the damage. Some chemicals are specific to specific insects. For example, while one chemical bait may control fire ants, it will not attract nor control carpenter ants. Also, determine the lifecycle, as different pesticides control different stages in the lifecycle.
A non-chemical approach (or cultural) can be implemented prior (or in addition) to using pesticides – and often in lieu of. Remove weeds and any debris that harbor insects, this eliminates breeding grounds and feeding areas. Plant alternate varieties each season (like crop rotation) to eliminate a constant food source for target insects. Proper use of water and fertilizer grow strong plants which naturally resist insect damage.
Some insect damage is not something to be alarmed at, as long as the plant can grow through the damage with no irreparable harm. That said, if the damage goes beyond the noticeable cosmetic to structural or yield (flowers) damage, then it must be addressed.
The same holds true with plant diseases, some are tolerable, and some are lethal. Here are a few plant diseases common to the Texas landscape:
- Leaf Spot: Spots can come in different sizes and colors depending on the fungal or bacterial causal agent. Some are circular with water soaked centers (bacterial), others are angular or circular with a dry center (fungal). In some the center lesion may fall out of the leaf leaving a hole. Start by using plants that are resistant to fungal diseases. You can further reduce the spread of leaf spot diseases via chemical control. In many cases, however, a plant may produce flowers all season long before the disease becomes so severe it would need to be removed from the landscape.
- Bacterial Root Rot: When a plant wilts even with adequate water, it can be indicative of root rot – which actually does starve the plant of water and nutrients. Root rot can often be prevented or eliminated by correcting the drainage and controlling watering habits (not over watering).
- Powdery Mildew: As the name implies, the plant will look to have a powder-like substance on the top of its leaves. Again as a fungal disease, it can be controlled with synthetic chemicals, or by cultural methods such as increasing spacing of plant material, morning watering (as opposed to evening), and irrigation/drainage management – all of which cut down on high humidity levels around plants.
To determine the health of any landscape, a soil test is highly recommended. The lab analysis will include existing nutrient levels, pH level, and organic material content. Texas A&M agriculture extension offers information on how to collect and send in your soil sample.
From the test results, you can create an effective plan that will replenish soil nutrient levels in line with the test analysis. This may include (though certainly not limited to) the addition of soil amendments such as organic matter to enrich soil profile. Remember when you amend the soil, plants process synthetic and organic fertilizers in the same manner.
In conclusion, now is the ideal time to begin assessing the health of your landscape. From evaluating your irrigation plan to looking for any potential threats to your plants’ health, a watchful eye will keep your landscape healthy and beautiful all season long.
For more information on Texas landscapes or for any questions you may have regarding your property, please feel free to reach out to us . Woodlake Outdoor – we strive to enhance the beauty, grace, balance, and generosity of nature.