Summer pests and diseases

Hornworm on a tomato plant.
Photo Pam Dawling

It’s August, which for us is the peak time for pest insects as well as for fungal diseases.

This year, we have been collecting Japanese beetles from our okra plants, to prevent the leaves getting stripped off. It seems to be working. Many plants can take 30% defoliation without a loss of yield, but some years, our okra plants end up as just a bunch of stalks, and you know that means almost no photosynthesis can happen. Japanese beetles are one of the insects that have an aggregation pheromone, so those commercial traps are not only gathering up your own Japanese beetles, but also attracting neighbors’ beetles. Sometimes this means no net improvement, as the newcomers eat crops before going into the trap.

Another bad summer pest here is the Harlequin bug, a brightly colored stink bug. We try to have July be “No Visible Brassicas Month” aiming to disrupt their lifecycle. We use insect netting over the fall brassica seedlings we sow in June, and we clear our spring brassicas before the end of June. In July and July we use netting over any new brassica transplants, and sowings of turnips. During August we remove netting from older transplants and sowings, on to newer ones, such as kale and collards.

Leaf-footed bug, one of the stink bugs. Photo Kati Falger

Here’s a link to an article on Stink Bug Identification and Management in Vegetables, from the Alabama IPN Communicator Newsletter. Read More

I wrote about squash bugs and cucumber beetles on our hoophouse squash in June.

Squash bug nymphs and eggs
Photo Pam Dawling

Margaret Roach at A Way to Garden has a good post on distinguishing between the tobacco and the tomato hornworm.

The tobacco hornworms, Manduca sexta, is close cousins with the tomato hornworm,

Both species eat Solanaceous crops (nightshades) such as tobacco, tomato, peppers, eggplant and potatoes. The differences are in the stripes and the horns.

We have tobacco hornworms (this land was a tobacco farm before Twin Oaks bought it 51 years ago. This year, for the first time, we haven’t had any hornworms in the hoophouse. We’ve pulled up our tomato plants in there – we only grow the earlies in there, as it’s plenty warm enough to grow tomatoes outdoors here from May to October. I might be celebrating too soon – we still have a bed of peppers in the hoophouse and I think I might have seen evidence of a hornworm at work, although I could not find the culprit yesterday.

Tomato plant badly damaged by hornworm
Photo Pam Dawling

Pictures of Tomato Spotted Wilt Virus and other tomato diseases

We’re always a bit anxious that TSWV might show up one day, but luckily it hasn’t. Meanwhile we forget what it looks like. Here’s a few photos on the Cornell Vegetable MD Online site.

And here’s a good collection of tomato disease photos on the You Should grow site.

Spotty tomato leaves. I think this is Septoria Leaf Spot.
Photo Pam Dawling

All the news is not bad! Here’s a satisfying photo:

Hornworm mother Hawk Moth trapped by a zipper spider.
Photo Pam Dawling
Zipper spider.
Photo Wren Vile

 

Hoophouse covered! Frost expected Sunday and Monday nights!


Photo credit Luke Stovall

Well, after two weeks exposed to the elements,  our hoophouse finally got its renovations finished, and we put the new plastic on this morning. I haven’t yet got the photos to prove it, but take my word for it, the stress is over! Two people are out there right now, finishing inserting the wiggle-wire in the channels round the edges, and trimming off the spare plastic. We’d all forgotten how hot it gets in there with plastic on! Suddenly no-one wanted to go inside.

This morning’s work went smoothly till we got to the second layer of plastic. Last night was cool and dewy, and the grass wet. As we pulled the second layer of plastic up and over the hoophouse, it got a film of dew on the underside – bad planning! The top layer than stuck to the bottom layer and was really hard to pull over. We turned on the blower to try to push some air between the layers, and we also wafted it ourselves. Eventually we were successful, but we did make a few holes in the edge of the plastic in the meantime.

Those who’ve never put plastic on a hoophouse might wonder how it’s done. Here’s our method: we tied ropes (thank you Twin Oaks Hammocks) around tennis balls pushed up in the edge of the plastic, like little Halloween ghosts. We used five along the 100′ length of plastic. Then we put more tennis balls inside colorful odd socks (thank you Twin Oaks Community Clothes) and tied the other end of each rope to one of these. Someone then threw the balls-in-socks over the top of the hoophouse to the far side. Hilarity at how many of us never learned to throw well! The first layer slid on quite easily, and we “tacked” it into position every ten feet or so with a piece of wiggle-wire. Then we repeated the ball-in-sock throwing exercise with the outer layer. That’s when it got difficult. And our bag of chocolate chips had to be moved to the shade because they were starting to melt!

After we got both layers of plastic in position, we pulled out the slack and fastened the wiggle-wires fully in the channels. The shiny new plastic looks beautiful in a techno-sparkly kind of way. And it promises to help us grow tons of delicious food for the winter. Thank goodness it’s done.The weather forecast suggests we’ll have frost on Sunday and Monday nights. We’ve got ginger and cowpeas growing in there – we don’t want them frosted.

Ginger growing in our hoophouse.
Photo credit Kathryn Simmons

The Asian greens, spinach and radishes can take it, but not the warm weather crops.

We’ll still have some odds and ends to finish up: one of the windows needs a repair to the frame, and the bubblefoil stuff along the north wall needs tacking back into place. All in all, though, a happy conclusion to this project.

It’s time to put rowcover over the late beans to extend the season beyond the first frosts. Photo credit Kathryn Simmons

Outdoors, we are bringing out rowcovers to cover late plantings of squash, cucumbers, green beans, lettuce. It’s goodbye to the eggplant, okra, sweet corn, tomatoes. It’s time to harvest the sweet potatoes and peanuts. Maybe it’s goodbye to galinsoga and other tender weeds. Maybe goodbye to harlequin bugs. The brown marmorated stink bugs are starting to seek shelter for the winter, in our sweatshirts hanging on the shed door.

Goodbye eggplant!
Photo credit Kathryn Simmons

Goodbye to all that. And hello to sweet potatoes, boiled peanuts (a seasonal tradition here), kale, spinach and leeks.

Hello kale!
Photo credit Kathryn Simmons