![\"ladybugs](\"https:\/\/gregalder.com\/yardposts\/wp-content\/uploads\/2018\/01\/IMG_20180116_111125-e1517438695731.jpg\")
<\/a>The kids love having so many ladybugs to pick up.<\/p><\/div>\n
Natural predators \/ Beneficial insects<\/b><\/p>\n
When I need information about a garden pest, one of my favorite resources is the\u00a0University of California Integrated Pest Management website.\u00a0On its page for these specific aphids<\/a>, it acknowledges that ladybugs along with\u00a0other predators of aphids like the syrphid fly<\/a> and the\u00a0parasitic wasp, Diaeretiella rapae<\/em><\/a>,\u00a0<\/i>are usually capable of controlling only very low populations. “Short crop life, use of pesticides for other pests, the tendency for the aphids to be deep within the head, and various other factors make it difficult for natural enemies to keep rapidly rising aphid populations from reaching economic levels.”<\/p>\n This perfectly aligns with my experience, unfortunately. I’ve never sprayed any sort of pesticide in my yard, but still natural enemies of the aphids can’t control them well enough.<\/p>\n \u00a0<\/p>\n What harm do the aphids cause?<\/b><\/p>\n But let’s back up and ask what\u2019s so bad about aphids, anyway? If allowed to colonize on a young brassica plant, aphids can grow to overwhelmingly high numbers and nearly kill the plant. They do this by literally sucking the juices from the leaves.<\/p>\n Aphids have nearly killed this cabbage.<\/p><\/div>\n At lower numbers, aphids are more of a nuisance than a killer. For example, I harvested this head of cauliflower the other day.<\/p>\n ‘Goodman’ cauliflower ready for harvest.<\/p><\/div>\n Before harvesting, I blasted the head with water because I had noticed a few aphids. But then, upon cutting the leaves away from the head, I turned it over to find hundreds more holed up in the florets.<\/p>\n More than a nuisance, more than gross, it was something of a heartbreak. Months of hopeful caring for the cauliflower plant had been ruined by the discovery of these invading insects.<\/p>\n \u00a0<\/p>\n Pattern of invasion<\/strong><\/p>\n Aphids invade a bed of brassicas in a curious pattern. I’ve observed this on every type of brassica I’ve grown, and it has occurred consistently every year. In short, the pattern is that adjacent plants have extremely variable levels of aphids. You might think that they’d spread themselves out among all of the plants, but no. There might be one that is terribly infested while the next, whose leaves are touching, has no aphids at all.<\/p>\n Romanesco on left, destroyed by aphids. Romanesco on right, ignored.<\/p><\/div>\n Because of this pattern, my approach to aphids in the past has been to just do nothing. I accept that they’ll decimate a plant here and there, which I then feed to the chickens (who also eat aphids), but they leave most untouched or barely touched. And having some aphids around as food for beneficial insects is smart, I’ve figured. I don’t want to try to eliminate them entirely. That has worked decently in the past, but not in a bad aphid year like this one.<\/p>\n \u00a0<\/p>\n Roguing and blasting<\/strong><\/p>\n This year, the aphid population and aphid damage has been too high for my standards. In the bed of Romanesco from which I took that photo, out of the six plants, three went to the chickens. Normally, it might be zero or one, max. So I’ve had to try out a couple of extra control methods.<\/p>\n “Roguing (removal and destruction) of infested plants from the field can be effective early in the crop cycle,” says the UC IPM page<\/a>. Instead of sacrificing a plant to aphids and leaving it in the bed, I’ve started to remove plants that are particularly attractive to aphids. As I said, they go to the chickens, so all is not lost. But I’d love to find out what it is that attracts aphids to some plants and not others right next door. Anyway, roguing has apparently been of some benefit over the last few weeks. It’s hard to tease out the effects of my roguing though because I’ve also started a more consistent regimen of water blasting.<\/p>\n Aphids are easily knocked from the leaves of brassica plants with a strong spray from the hose. I put one hand under the leaves of young plants to support them, and I also make sure to lift leaves to spray the undersides, where aphids often hide. Another place you can’t forget to blast is within the rosette of tightly curled leaves in the center of the plant. After the storm, you can see the graveyard beneath a plant.<\/p>\n<\/a><\/a><\/a><\/p>\n<\/a>