hornworm – Sustainable Market Farming

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

Vates dwarf Scotch curled kale Photo by Kathryn Simmons — Vates dwarf Scotch curled kale
Photo by Kathryn Simmons

This is what we’re aiming for – healthy kale plants to feed us during the winter! I reported last week that we had got one bed of kale sown. It’s up nicely under the rowcover, so we can use some of those plants as transplants to get more beds established when we do manage to get more beds tilled and prepped. Yesterday we sowed more kale – three partial beds which had held our fall broccoli and cabbage transplants.

We have at last got our final row of cabbage planted out, so the nursery seed beds are fairly emptied out. Not entirely though. Our next transplanting job is to fill gaps in the rows. We have 8 rows of broccoli and 4 of cabbage, 265 ft long. A hundred people eat a lot of food! Meanwhile, we raked around the remaining broccoli and cabbage transplants, and sowed more kale. A bit chaotic, having beds with big old plants and freshly sown ones, but manageable. all are covered with spring steel hoops and ProtekNet insect exclusion netting made by Dubois Agrinovation., which I have raved about previously. It keeps Harlequin bugs and flea beetles out.

We like Vates as it’s the most cold-hardy kale we’ve found and we can leave it outdoors without protection in our zone 7 winter and harvest from it about once a week. One year we did try covering it with floating row cover, to boost production, but it was a sad mistake! The fibers of the polypro row-cover got snagged in the frilled crinkled leaves, which made the cooks very unhappy!

Last winter we grew some Beedy’s Camden kale from Fedco

Beedy’s Camden kale.Credit Fedco Seeds

It was faster growing than Vates, and the leaves are wavy rather than frilled, and some people liked a change from our usual. Rated as hardy to zone 5, it wasn’t as cold-hardy as Vates in our garden. We are growing some more this winter.

We had planned to try Blue Ridge kale from Osborne Seeds, but they had sold out by the time I tried to order. It has done well for Clif Slade at his 43560 Project at Virginia State University, where the climate is a little milder.

Blue Ridge kale. Credit Osborne Seeds

While shopping, I bought some Black Magic kale. We have tried these Lacinato kales in the past, both outdoors and in the hoophouse, without much success. We’ve had aphids building huge colonies in the curled back leaf edges. We’ve had indifferent growth. I’ve tasted great Lacinato kales at friends’ houses, outside our region. But every few years it come time to try a previous failure again, and we have some new crew members enthusiastic about this one, so we’re giving it our best!

Black magic kale. Credit Osborne Seeds — Black magic kale.
Credit Osborne Seeds

Two weeks ago I asked if anyone knew if zipper spiders ate hornworms. I did some reading, and I think it’s possible they do. The Latin name for these spiders is Argiope aurantia. I found out that all the many, many zipper spiders I’ve been looking at are females. The males look quite nondescript. I also confirmed that the 3/4″ brownish sacs we had hanging all over the hoophouse all last winter were indeed egg sacs of the zipper spider. Each one held over a thousand eggs! Golly! This is better than science fiction! Wikipedia says prey can include not only insects, but also small vertebrates such as geckos, so it seems likely that hornworms could be on the menu. Does anyone have a good source of information? There’s a YouTube of a spider eating a hornworm. I haven’t got enough bandwidth to watch it. Let me know if it’s good.

Zipper spider on tomato plant. Credit Wren Vile — Zipper spider on tomato plant.
Credit Wren Vile

Tag: hornworm

Summer pests and diseases

Sowing kale, finishing planting cabbage, more on zipper spiders