Posts Tagged ‘tomato potato psyllids’

 “May you live in interesting times,” is a curse that seems to dog gardeners this summer.  If late snow, shredding hail, and humid conditions weren’t enough, Mother Nature is now sending a wave of insects to perk things up in the tomatoes. 

Tomatoes top the list for most kitchen gardeners, ranking number one in popularity across the country in a recent National Garden Bureau poll.  With thousands of love apples blanketing the area, it’s no wonder the Front Range is a hot place for psyllids to take their summer vacation. 

These tiny tomato boogeymen have begun assaulting plants this season in what may be the vanguard of thousands of migrating psyllids (Bactericera cockereli).  Dr. Whitney Cranshaw, Professor of Entomology at Colorado State University, has seen large numbers of these insects several parts of the state, including Larimer county.  Sightings of the insect have also been reported in Louisville and north and south Boulder gardens.  

A classic sign of psyllids is their waste, called lerps.


The aphid-sized adults are lovely, with jewel-toned eyes and dark abdomen banded in white.  Their young, yellow at hatching, gradually turn green with each molt; being flat and elliptical they look like scale.  Though adults move about actively and fly in migration, the young are sedentary, content to sit quietly, feed, and excrete white, waxy frass that resembles sugar. This is their waste, called lerps, and is an easy to see clue that your plant is being attacked. 

We should prepare for their arrival in our area soon, since these small, winged sap-feeding insects have toxic saliva that causes the plant to grow oddly.  Look for leaves turning yellow with purple veins, fruit that’s small and tasteless, or the plant appearing as if sugar were spilled on it.  

  Start scouting your plants, carefully checking them for insects or disease every three days until you spot signs of trouble.  Psyllids can mean big problems for tomatoes, severely stunting fruit; so at the first sign of them begin spraying plants with insecticidal soap to keep them at bay.  Coverage of both upper and lower leaf surfaces is crucial to control, and may not be enough. 

Dusts of sulfur can help, if care is taken to cover all leaf surfaces, but should the insects get the upper hand, stronger products with pyrethrin or esfenvalerate can be used.  

 Several diseases show up in gardens at this time.  Green plants turning blonde by yellowing from the lower leaves upward should be closely examined.  If they have brown spots with concentric rings, suspect early blight (Alternaria solani). 

Water, insects, and gardeners spread this fungus.  Pick off diseased leaves and keep the ground free of debris. Dust healthy leaves with sulfur to shield them from infection.  Once the plants have gotten three feet tall, pluck off leaves in the lower foot to prevent the spreading climb of the fungus.  Give plants room to grow without crowding them, and use drip irrigation to prevent splashing water.   

Black, sunken, rotten spots on the bottom of fruit are blossom end rot, a disorder caused by poor uptake of calcium.  Though calcium is plentiful in our soil, irregular watering and excessive heat prevent the plant from using it.  The key to control is watering consistently, so use a timer to automatically turn on and off the irrigation.  Mulch plants to keep the soil from drying out too rapidly.  

More information on tomato troubleshooting can be found on the Colorado State University Extension website.

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Today’s blog post can be heard on the public radio show Crop to Cuisine, hosted by Dov Hirsch. 

Crop To Cuisine

A friend of mine sent me a link to a story on foods to be featured in Minnesota this summer.  It seems that 2009 is the year of the potato for those folks up north.  This doesn’t sound like a bad thing, except that at the Minnesota State Fair, most of their foods are served on a stick.

 Oh what an indignity this is for the noble spud, to be skewered like a vampire with a stake through its heart.  The food they’ve concocted – like the “Fry Dog,” where French fries are glued by batter to a hot dog and then the whole thing deep fried, or the “Texas Tater Dog” with a spiral cut potato wrapped around a German sausage before frying – can only be described as a cardiologists’ nightmare.

 Why do this to a sweet, flakey, creamy spud?   New potatoes

We’re nearing the start of new potato season in Colorado, when young tubers can be tickled from the ground.  These fingerlings can be dug two to three weeks after the potato plant has finished blooming, which the earliest varieties of potatoes have just begun to do.  When digging, you often have to lift the entire plant to get at the tubers, but in softer soil you can gently brush the soil away from the hill, harvest only the largest of the fingerlings, and replace the soil to let the rest of the potatoes grow.  Potato flower

 Be careful when digging up new potatoes; their skin is thin and easily bruised.  Keep them out of the sun so they don’t turn green by taking them immediately into the kitchen. 

 Potatoes growers in Colorado may not have to worry about wild eyed northern barbarians showing up to skewer their spuds, but you do have to contend with another bane of summer:  psyllids.  These insects don’t winter here – they’re tourists, arriving in mid-summer from another state, laying claim to the best camping spots, inviting all their friends and family, letting the kids run wild, gobbling up our resources, then leaving the place looking yellowed and spent.  

 But in this case the tourists are psyllids (Bactericera cockereli), small, winged, sap feeding insects whose toxic saliva causes the plant to grow oddly.  Their young look like scale – flat and oval.  The tiny adults are dark with big, jewel-toned eyes and lighter bands on the abdomen.  

 Psyllids migrate northward during summer – coming up from Texas, Arizona, or New Mexico – arriving in our area to wreak havoc on potatoes and tomatoes.  Look for leaves turning yellow with purple veins, or the plant appearing as if sugar were spilled on it.  This crystalline dust is their waste, called lerps, and is an easy-to-see clue that your plant has become the vacation destination for these bad bugs.    lerps

 Psyllids can mean big problems for potatoes if they’re attacked after tubers have started developing, stunting growth and creating oddly shaped spuds.  If harvested, the potatoes from infested plants don’t store well, sprouting prematurely.

Scout your plants – carefully checking for insects or disease by lifting leaves examining them.  Check all of your plants every three days, and at the first sign of trouble, begin spraying with insecticidal soap to keep insects at bay.  Coverage of both upper and lower leaf surfaces is crucial to control, but may not be enough.

 Should the insects get the upper hand, move up to sprays containing an extract of neem oil.  Make sure your spray won’t harm plants by checking the label to ensure it’s listed for use on potatoes, then test it on a leaf or two a couple of days before spraying.

 With these tips your spuds will grace your table with dignity, and sticks are purely optional.

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