Thrips: Tiny Pest, Big Impact

Walking through the lawn and feel a sharp bite on your arm only to look down and see nothing? Look a little closer: that tiny beige freckle is moving! Thrips are itty, bitty winged insects that will feed on most any plant, and are happy to take a taste of you from time to time. They are easily controlled with a good balance of predatory insects like lacewings, but can kill vegetation if allowed to populate out of control. According to the Texas Organic Vegetable Gardening book (a must own for all Texas veggie gardeners) thrips

attack buds and tight-petaled flowers such as roses. They are barely visable to the naked eye but will rasp the plant tissue and drain teh sap. Heavy infestations can kill plants... Controls include seaweed, lacewings, citrus and neem.

How do you determine thrip damage? The sap suckers will leave leaves with a mottled appearance and can deform leaves and flowers. You may see runner lines on the underside of the leaves and sotty debris from their droppings. My early tomatoes had trouble setting their flowers last year: thrips were to blame. Thrips can also cause problems by spreading disease from plant to plant. If you notice a spread of wilt throughout your garden, you may have thrips to blame. This image shows thrip damage on cucumber plants:



I think i may have just determined what's plaguing this year's cucumber crop in my own garden. Here's my cucumber:



Looks pretty similar, ay? I had some weeeiiiird disease looking deformation in my cucumbers the year before last: twisted up flowers and mangled leaves. I'm thinking thrips may have been to blame then as well. I did spot some small leafhoppers on the leaves, so this damage may be due to them or a combination of the two pests. Thrips are more likely to descend effectively on your crops when they're suffering from dryness. Another reason that automated irrigation, preferable at the soil level is so important to the health of your garden. Thrips are also attracted to pink and blue, making them common pests for flowers like petunias. You can control or at least ID your problem as thrips by placing bright blue or pink cards sprayed with sticky trap at intervals in your garden. Another useful control for thrips is allowing dry, weedy areas to remain outside of your garden. The thrips like the dry, unhealthy grassy weeds (another reason you'll feel the stingy thrip bites while walking through droughty lawns) and will leave your vegetables alone.

Our massive drought is definitely taking a toll on my (unautomated) garden. Plants are stunted due to lack of consistent water, and pests are staking their claims. The natural predators usually found in force in my garden (toads, anoles and predatory insects) have been hiding from the heat themselves  and aren't doing their jobs as well as i normally expect them to! To be honest, i've just about had it with this season. I'm so happy to see some of our clients' gorgeous gardens on a weekly basis. Despite the drought, their gardens (with automated watering) are really popping and utilizing this heat and sun to set early harvests. For the rest of us struggling through the heat - it's time to start seeds for Fall. Let's hope that season does us a little more kindly.

Some very excellent photos of various species of thrips and their damage can be found on this site. Perusing this page makes me realize I have a lot more thrip damage on a lot more plants than I ever thought. Onions, citrus, cucurbits and beans all show signs of thrip damage in my garden. Dang!

Articles with useful information on thrips:

• Missouri Ag Extension
• Controlling Garden Pests
• UC Davis

This post can also be found at Yard Farm Austin.

Southern Pest Spotlight: Chinch Bugs

Have you noticed large areas of yellowing and dying grass in your lawn? Do the areas seem to be spreading and getting larger? Your lawn may be suffering from brown patch, but chinch bugs may also be the culprit. Chinch bugs are most damaging to St. Augustine grass, but can be found in other types of lawns. Our early, record breaking, rain lacking heat wave is the perfect breeding ground for all kinds of pests, especially the chinch bugs. Here's a little about chinch bugs:

Chinch bugs overwinter as adults in various protected areas, particularly among weeds and grasses near fields. Adults emerge in the spring and deposit eggs singly behind the leaf sheath or in the soil at the base of the small grain crop plant. In a few days, the eggs hatch and the nymphs begin feeding on all parts of the host plant from the roots to the uppermost leaves. The nymphs undergo six developmental stages, the last being the adult stage. Two to three generations occur per year, the later generations migrating to corn and sorghum when small grain crops become dry.

The chinch bug pierces the plant with its moth parts and sucks out the plant sap. This feeding prevents normal growth and results in dwarfing, lodging, and yield reduction. Severe infestations during early development may cause plants to wilt and die prematurely. Most injury is caused by the six nymphal instars.

- Oklahoma State University

According to The Texas Ag Extension Office the symptoms of chinch bug damage differ from brown patch symptoms which usually occur in a circular or semi-circular pattern. Chinch bug feeding causes irregular-shaped areas of dead and dying grass. Chinch bug damage also can be difficult to distinguish from that caused by drought. Detection of significant numbers of the insects themselves is the best proof that chinch bugs are the cause of the damage. The Natural Gardener is happy to take plugs of soil dug from your yard to ID with their fancy microscope. They recommend digging a square foot or so of soil from the border of one of the patches: include soil from the dying and the healthy areas of your yard. But once you ID the nasty little buggers - what is there to do about it?

Controlling chinch bugs starts with prevention. Aerate your lawn regularly and don't allow a thick bed of thatch to build up, providing perfect habitat for the eggs and adult bugs alike. Mowing properly helps to reduce thatch as well - by 'mowing high' or only cutting off 40% at most of the grass blades, you'll be placing less green matter back on the lawn to turn into thick thatch. Mulching mowers are also a fantastic option. Don't over fertilize your lawn. Over-application of fertilizer also contributes to thatch formation and makes lawns more attractive as a food source for chinch bugs. Chinch bugs thrive in heat stressed lawns, so remember to water your lawn appropriately and consider top dressing with compost in the early spring to help with water management and overall health.

If you can't prevent chinch bugs, you'll have to control them. There are natural and organic methods including promoting diverse and organic habitat for beneficial insects including big eye bugs, assassin bugs and ants. Consider insecticides as a last resort, as they will devastate the populations of these beneficial insects.

For a very thorough explanation of chemical control of chinch bugs, please visit the Texas Agricultural Extension's page on the subject. Pesticides should never be used without taking safety precautions and being absolutely sure that the pest your treating is the pest that is damaging your lawn. Knowledge is power!



Have you seen chinch bug damage in you rlawn? What do you plan to do about it?

This post is also found at Yard Farm Austin.