Wednesday, June 11, 2008

Lettuce bolting... tomatoes smoking

Lettuce is a wonderful garden crop. Easy to grow. Makes a crop in as little as 28 days. And if you find a good seed catalog you'll find dozens of lettuce types... stuff you don't even see in the stores. Almost nothing bothers lettuce except the occasional slug... and hot weather. The recent heat wave and lengthening daylight periods has caused my lettuce to "bolt". Bolting is the natural inclination of lettuce to form seed stalks under long days and high temperature. So there was a mass harvest in my garden and everyone I know is getting a bag full. Fortunately, I have seeded lettuce several times and the less mature plants are still coming on. Plant breeders have improved heat tolerance in lettuce varieties and this helps. For tips on growing lettuce check out Penn State's nifty fact sheet called growing leafy vegetables.

Some like it hot. Tomatoes, eggplant, peppers and melons thrive under the conditions we're having right now. You can just about see tomatoes plants grow before your eyes! Even the most tender vegetable crops should be in the garden now. Many gardeners used row covers and other devices to get a jump on the growing season, especially with these cold sensitive crops.

Tomatoes are almost as fool proof as lettuce, but we had a call in the Bucks County Extension office today describing a complete disaster. Twenty-five tomato plants went in... twenty-five are wilting. Same thing happened the previous year. While you will read and hear about Verticillium wilt and Fusarium wilt, these tomato diseases are now a rare occurrence because plant breeders have done a fantastic job breeding for resistance to these problems. So what was up? A quick look at our references came up with a possible cause. Question? Was there a walnut tree growing next to the tomato patch? Answer. Yes. Mystery solved! Walnuts produce a toxin in their roots (as well as leaves and other plant parts) that is deadly to tomato. Doesn't happen often but there it was. A CSI moment. Our web-based tomato fact sheet appear to be under revision but we'll mail you an old fashioned paper copy if you call 215-345-3283 and request it.


Kathleen said...

Speaking of hot weather garden plants and row covers, I've heard that there's a critical period of time to cover squash with row covering in order to prevent squash vine borer -- do you know about that technique, and if so, when the critical week takes place?

Scott Guiser said...

Squash Vine borer is a real problem in home gardens but the row cover is not a good option.It is just too hot to cover plants with row cover now. You'd injure the plants. Penn State's fact sheet gives the life cycle of this pest and some management hints. The important points are that this pest will emerge from soil in mid to late June in Pennsylvania and lay eggs at the base of stems of summer squash, in particular, and some other squashes as well. Applying an insecticide(carbaryl,permethrin) to just the base of plants, where the stems enter the soil, in late June and again in early July provides protection. No need to apply to the entire plant. Avoid treating flowers. Or, you can plant a lot more squash than you need and take your lumps. Finally, if you are into surgery, slit open infested stems and stab the borer larvae before they do extensive damage. That can be difficult because some plants have multiple borers inside and the surgery may kill the patient. And if all else fails, vist a lcoal farm and by some.See you Fresh From Farms directory
By the way, if you're observant, you may see the adult stage of this pest which is a pretty black and orange moth about 1.5 inches across. Look for them resting on squash leaves and eyeing up your plants as a materity ward. The books say thay can lay up to 150 eggs.