Weeds and bugs. With severe irrigation cutbacks mandated during this fourth drought year, we just might have more weeds and bugs in our gardens this summer than lawn grass and ornamental flowers or fruits and vegetables. Weeds and pest insect populations can actually increase during dry years. Control for both begins with early detection and early efforts at eradication.
Nutsedges proliferate in damp, overwatered soil, but because they produce tiny root bulblets or tubers that hold water, they can remain dormant in dry soil for up to four years. Herbicides that translocate to the tubers when they are small are most effective when the nutsedge blades are just two inches tall and when there are just two or three blades.
Spotted spurge is often the first summer weed to appear when temperatures warm. Like many weeds, spurge thrives in harsh conditions, grows rapidly, and each seed head produces thousands of seeds that remain dormant on the soil until conditions are right for germination. Monitor bare areas for the first spurge leaves and use a wiggle hoe to regularly cultivate the top inch or two of the soil surface. The tough spurge roots may resprout, but after two or three early cuts the roots should die off.
The drought-tolerant summer weeds (dandelions, purslane, oxalis) that sprout in well-mulched areas are germinating on the mulch surface. Weeds seeds that lie below mulches don’t receive the sunlight necessary for germination. Root systems of these surface weeds tend to be weak and spindly and are easily hand pulled before they set seedheads.
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Check the UC Davis weed gallery on their website (www.ucipm.ucdavis.edu) for excellent photos of weeds, their seeds, their root systems and all stages of their development.
Most gardeners are curious about nature in all its forms. Curiosity will help you with early detection of pest insect populations, before you see obvious damage. Learning to identify egg sacs or egg masses and to recognize and control for pest insects in their larval, nymph and adult stages will help control populations before they can cause damage.
Egg clusters of many larger insects are easily seen and can be destroyed without the use of pesticides. Nymphs and larvae are more vulnerable than adult insects to lesser-toxic pesticides such as insecticidal soaps, neem oil and horticultural oils.
Two types of stink bugs, the Bagrada bug and the leaffooted bug, are fairly recent arrivals in the Central Valley. They are sucking insects that feed on plant juices Both stinkbugs produce multiple generations every year and the generations can overlap, leading to nearly endless damage during the growing season. As adults, they can fly away from pesticide sprays and are difficult to eradicate, but their egg clusters and nymphs are more easily destroyed.
The UC Davis website provides photos of pest insects in all their stages and information on host plants, damage descriptions, how to search for and identify the egg clusters and the nymphs or larvae, and how best to reduce populations. Just remember, early detection and early control for pest insect populations will really help prevent major damage in your drought-stressed garden.