Thursday, April 28, 2016

Two great Montgomery County events this weekend

Hear more from the Montgomery County Master Gardeners at this link:

Monday, April 18, 2016

Edema on pepper seedlings

One of our demo garden MGs brought a pepper seedling leaf in last week with small bumps on the bottom, near veins. It looked healthy otherwise and didn't have apparent active insects. Then the same thing happened to my pepper seedlings, so I decided to look it up.

The issue appears to be edema, which is an abiotic problem usually resulting from overwatering. Basically, the plant takes up water faster than it can use it. With a mild case like this, the simple solution is: don't water as much! If it persists I may also try adding calcium as a deficiency of that mineral can also be a factor.

Here is an article on edema from U. Conn. (doesn't mention peppers specifically, but I made the connection through a hot pepper growing forum, and the many photos similar to mine on the web also help with diagnosis). And on UMD's HGIC, results of edema at a later stage.

Seedlings are best watered deeply and then allowed to dry out on the surface before watering again. This also helps keep fungus gnats away. Make sure your pots have adequate drainage holes and water doesn't sit in the trays.

My pepper seedlings are beautiful and large! Too bad it'll be another month before I feel comfortable planting them outside...

Wednesday, April 13, 2016

New pest of garlic, leeks onions found in PA

Breaking news from Jerry Brust, UME IPM Vegetable Specialist:

"Hello Everyone...another new pest--the Allium (or onion) leafminer has been found in Pennsylvania. It seems to be worse in organic systems and in home gardens, but it is something we should watch for over the summer and fall. It seems to like leeks the best, but will infest any allium spp. Its population appears to build through the spring and summer and can become quite high on some farms that do not spray any insecticides."

Link to a full IPM report with photos from Penn State Extension: 

The report is for commercial growers (organic and conventional). Home gardeners in MD should focus on scouting for this pest and reporting any finds to HGIC. Covering early spring  alliums with floating row covers will help exclude the allium leafminer and other pests, such as onion maggot.

Friday, April 8, 2016

Effects of light, cold, and wind

Every once in a while we gardeners get a clear illustration of the effects of environmental factors in the growth of plants. Here are two that happened at my house recently - I'm sure you can come up with lots of additional examples.

I seeded 'Pomegranate' lettuce in March and transplanted the seedlings into 2-inch cells when they had first true leaves. Then, due to space issues, I put half the seedlings under lights inside and half out on my enclosed back porch (it has vinyl windows that slide down over the screens, so is protected from wind, but only a few degrees warmer than outside). The back porch seedlings got direct morning sun but no additional light. Here's the difference a couple of weeks later:

back porch

The back porch seedlings will be fine for transplanting in another week or so, but they'll take some time to catch up to the others. Both the warmer temperatures inside and the close-up light over the seedlings made a huge difference.

Another more severe effect happened during that day-long blast of frigid wind on Tuesday. I went out in the morning and walked under the arbor where my Siberian or kolomikta kiwis grow (different species than the larger hardy kiwi, Actinidia arguta, but with a similar zone range, i.e. perfectly hardy in 7a). Everything looked fine then, but when I next looked in the late afternoon, nearly all the leaves were badly desiccated by the persistent wind - or frozen, or both.

They still look like this today. I'm hoping to see some recovery in the next week, but it's possible the plants will lose the leaves and flower buds. They've been doing fine for several years, so I guess we've just never had that particular kind of wind at this time of year (or stage of leaf growth) before.

I must add that the Derwood demo garden team was also blasted by the cold and wind on Tuesday morning - our first workday of the season! - but at least we could go inside to warm up. No such luck for plants.

Wednesday, April 6, 2016

Book review: Pawpaw by Andrew Moore

Pawpaw: In Search of America's Forgotten Fruit is a study of contrasts. Pawpaws (Asimina triloba) are a native North American fruit with an exotic, tropical taste and appearance; they have been eaten by Americans for millennia, and are a new, hot trend; they grow wild and plentifully but keep getting lost. Some people know them well, as a part of environment and diet since childhood; many have never heard of them, or know them only as a mysterious word in a song. A lot of us have been "way down yonder in the pawpaw patch" without realizing it. Ever walked along the C&O Canal? Pawpaw trees all over - and you'll find them in the understory of wooded areas in many places in Maryland and throughout the "pawpaw belt" of the southern and midwestern U.S. Fruits usually ripen in September - go looking!

In the course of writing this book, Andrew Moore traveled the pawpaw belt, finding wild pawpaws and domesticated ones, festivals dedicated to the fruit and places where it's present but ignored. The book provides a lot of interesting information about the pawpaw's history, genetics, and potential uses - which are not just culinary, as chemical compounds present in the fruit have medicinal possibilities. But the bulk of the book is about people and pawpaws: foragers and farmers, brewers of pawpaw beer, scientists, plant breeders, cooks, and so forth. From the USDA's "Johnny Pawpawseed," Neal Peterson, onward, there are a lot of people in this country devoted to the pawpaw, and Moore has apparently met most of them.

The Maryland chapter includes a brief interview with UMD Extension's own Stanton Gill, and an in-depth exploration of Deep Run Pawpaw Orchard in Carroll County, run by Jim and Donna Davis. I got to visit Deep Run recently as part of a fruit growing class taught by Stanton - here's a photo of the Davis' pawpaw orchard in March (yes, it was snowing):

In summer those trees will be covered with enormous, tropical-looking leaves and the orchard will be fluttering with zebra swallowtails. Pawpaw is their host plant, which is a good reason to plant the trees even if you don't care for the fruit. (Grafted, carefully-bred trees like the ones at Deep Run produce large fruits with a sweet banana-mango taste - as do some wild plants, but with wild genetics you may also get small, bitter fruit.)

If you like books about American history and culture with a generous side of science, horticulture, bushwhacking, and food, you'll enjoy this story of a fascinating native plant.

I have several pawpaw trees growing in my yard, only one of which is large enough to flower - and you need two to produce fruit, so I'll be waiting a while longer (or borrowing pollen from a friend's trees). Mine are seedling trees, so I don't know what quality of fruit I'll get from them. I'm thinking of ordering a grafted tree or two to plant as well. Jim Davis recommends 'Shenandoah' - if you've had experience with other varieties, please leave a comment!

Friday, April 1, 2016

Scout for leafminer eggs on spinach and beet this spring

Gabrielle Rovegno with Crossroads Community Food Network, sent in these photos of spinach leafminer (Pegomya hyoscyami) eggs on the undersides of beet leaves. The plants had been growing in a hoop house over the winter which explains the early presence of leafminers.
This very common pest of beet, spinach, and Swiss chard is a type of fly. The maggots hatch out and feed between the upper and lower leaf surfaces producing serpentine and blotch mines. It overwinters in the pupal stage with adults emerging and mating outside in April/May.

Locating and squishing these egg masses will help reduce their population. Row covers placed over seed beds and new transplants can help exclude the mated females and prevent egg laying.
Two egg masses on underside of beet leaf

Eggs are white and eliptical in shape

Grow your own gin and tonics

Today, April 1, the Thompson & Morgan seed company, famous for grafting various Solanaceae together, very seriously announced the development of a new product - the Gin and Tonic Tree:

which grows juniper berries and quinine bark on the same plant. Maybe.

(Hat tip to The Unconventional Gardener - more First of April at the link.)