Category: Advice - Fruit Horticulture
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More Etrog-Growing Tips
Readers have asked that I expound in more depth about pests and fruit propagation.
Scale and aphids are the most problematic pests for etrog trees. The young, green, fleshy stems at the growing ends of the etrog tree are favored targets for these insects, along with the bottom surfaces of leaves; both actions will suck the life juices out of the plant, causing extensive leaf drop and eventually plant death. The older stems, usually covered with a hard, brown sheath, are not usually affected.
In many cases, aphids are placed on etrog stems by ants, who "farm" aphids for their food value similar in intent to the way cattlemen husband beef cattle. Scale is a similar insect, which can colonize on an etrog plant by itself and will do the same type of thing to the plant: suck the life out of it. I've seen stems and leaves completely covered in scale and/or aphids.
While here in the Northeast aphids and scale tend to build up in the winter and early spring on plants that are growing inside, elsewhere they can appear at anytime during the year. Aphids and scale look like brown or black bumps, less than 1mm, on stems or leaves. Etrog stems should be smooth with absolutely NO bumps, leaves should show the veins, but no more.
To rid the plant of these insect parasites, I use a water-based fruit and vegetable pesticide, spraying the entire plant, stems, leaves, and dirt at base of plant. I do this outside (I won't use the spray in a greenhouse or inside a residence: the sticky, oily residue gets all over). After it dries, I leave it for a day to let the pesticide kill the aphids and/or scale.
Then next day I carefully wipe the dead insects off of leaves and stems, to make sure the insects are dead and to prevent mold/mildew from colonizing the dead insect bodies. Leaves that are too infected I pick off and destroy. Cleaning your etrog tree this way will restore a sick plant and greatly enhance it's growth. Once you find this is happening, you will have to clean your etrog at least once a year this way.
Although etrogs are self-pollinating and don't need another etrog tree nearby to reproduce (vs. something else like a Holly), creating fruit is a very iffy affair in our area, since both temperature and growing season are definitely not Mediterranean. If you are growing etrogs here, usually the best you can expect is a large, tall (8ft), heavily-leafed plant that is unsure whether it is a shrub or a tree...but no fruit.
To get fruit, or rather to allow the dozen or so self-pollinated flowers you will get each summer season to grow into fruit, you will need the proper environment: a long, mildly-warm growing season, well-drained loam, rich in nutrients, acid pH, moist breezes from the Mediterranean (etrogs don't like to be misted).
Creating fruit can be done in a less-than perfect cold, raw environment like the Northeast, if you are able to vary the ratio of red/far-red wavelengths in the light the plant receives, in order to "trick" the plant into thinking it's growing somewhere else, like in Calabria or Morocco, not in a south-facing window in a 7th-floor walk up in Brooklyn.
This will require a hothouse and some pretty expensive and sophisticated equipment, items not usually purchased or used by most people. If you want more information on doing this, the best advice I can give you is to check with your local University's botany department - their plant researchers usually do this type of "forcing" on plants all the time and can help you find suppliers for equipment and help you find the right ratio of red/far red for your etrog plant. Good luck. (This, btw, is why etrogs used for Sukkot cost so much: getting the tree to fruit at the right time, and the fruit to ripen at the right time, and to get lots and lots of fruit to sell, takes expertise, lots of care, and luck. It's an art, really.)
Growing Etrogs: 2013 Tips and Findings
Over the years, we've discovered that etrog trees need a loamy soil that provides a moist, but well-drained environment to root in. You can test your own soil using a simple, manual method as follows:
1) Moisten a handful of soil and form into a soft ball. Try to squeeze it into a flat ribbon. If it won't form a ribbon-like structure, your sample has too much sand in it. If the ribbon breaks after 2 inches or so, it's just right for etrogs, i.e. loamy, which means it has the right proportion of sand, organic matter and clay. If your ribbon reaches 3 or more inches, it means that the soil has too much clay in it and it will have a drainage problem. You can amend a soil with too much sand or clay in it by adding compost in a 1:1 ratio to get a composition that will be better for growing etrogs.
A dozen earthworms per 1 cu. ft of soil is just right for etrogs. Dig up a hole, 1 foot X 1 foot X 1 foot, in the area you want to plant your etrogs in. Break up the soil and look for earthworms in it to get a count. If the worm count is too low, add more mulch to attract more worms. Sometimes a low worm count can be caused by insecticides, fumigants or other chemicals in the soil. If this is what's going on, and this can be common in former tobacco fields in Connecticut, you'll need professional soil remediation.
Fill the hole you dug to count worms above with water to the top. If the water level doesn't drain out to the bottom in an hour, the area may have a drainage problem, which will result in rotted roots if you plant etrogs there. So if this is a problem, plant somewhere else.
Etrogs in Pots - Placement Issues
Etrog trees in pots should not be placed on concrete or blacktop, since the pot will get too hot in the sun and the roots will get scorched. The best place for placing etrogs outside (potted or not) is behind a tree, preferably on the north side, with some morning sun from the east side, a midday course in the light shadows, and a late-day course with direct sun coming from the west. If you can, remove the pot's base and let the pot rest directly on the top of the soil.
When To Place Etrogs Outside
In New England, the best time to place etrogs outside is when the cotton willows drop their cottony seeds in the Northeast, usually around late May or early June, well past the time when frost could appear.
When To Take Etrogs Back Inside
At the end of the season, we take out etrogs and place them in pots (if they aren't already in pots) and bring them inside. The time to do this is when the outdoor temperature consistently stays around 45 degrees during the day (etrogs are amazingly resistant to cold after a summer season). We try to place them next to north- or west-facing windows, so they don't get much in the way of direct sun. Try to place them in an area free of other species of plants - they like their own space or will tolerate other plants, as long as they are other etrogs.
We've found the most damaging pests to be aphids. You can usually tell if a plant is infected with aphids by looking for these scaly, immobile insects on stems. You can also tell that aphids may be present by the presence of numerous ants crawling on the leaves and stems - ants farm aphids for their sweet exudate, which the ants use as food. Kill aphids using an insecticidal soap or a water-based vegetable and fruit insecticide. After the aphids have been killed, you'll have to wipe off their bodies from infected stems using paper towels or cloth wipes - the aphids will stay stuck on the stems until you do so, damaging plant tissues and impeding etrog growth.
Getting Ready For Etrog Season 2012
I've been preparing for growing new etrog plants in 2012. One of the most important tasks is to extract the seeds from the etrog fruits that I've collected from friends and family after the Sukkot holiday.
Cutting the seeds out of an etrog can give you a new appreciation for the etrog. A typical fruit can yield 40-50 closely-packed, misshapen, yellow-tinged seeds. Unlike a lemon or an orange, etrog seeds can be located anywhere in the flesh of the fruit, not just along the center axle. They're pretty slippery, too, and it's not unusual in my house to find "escaped" etrog seeds all over the kitchen and dining room floor in the months following seed extraction.
I used to have low germination rates (<5%) when I first started growing etrog trees. I found out that the reason for this was that I had been placing the seeds into the refrigerator before planting them, as I would for several other plants I'd been growing.
Etrog seeds do not need to be put into the freezer or refrigerator, like many other plants do, to trigger the seeds to sprout for the next year. You can leave them out, in a container like a bottle or glass, in a dry and cool environment during the winter. Now my germination rates are much better, averaging about 60%.
The etrog seeds in the above picture came from must one etrog fruit. They are in a glass (labeled at the bottom with the type of etrog they came from and the date they were harvested) which will be kept in a cool and dry place until Tu B'Shvat in 2012.
Etrogs shouldn't be planted too early in the winter, otherwise you end up with vigorously growing seedlings in the middle of the winter which will then lack the warm sun and rain they need to grow further on down the road. Then most of them will die. So, wait until sometime in February; I put the etrog seeds into peat pots around the Jewish holiday of Tu B'Shvat.
Tu B'Shvat starts the evening of the 14th of February in 2012. This holiday is considered to be the Birthday of Trees (see the article about this holiday elsewhere in this blog). When you put the seeds into the peat pots at that time, you can be sure that they will have germinated and have grown big enough to be put into cold frames come the middle of April later on.
Non-Kosher Etrogs Being Sold As Kosher
A note about growing etrogs for commercial use. This year there were a lot of non-kosher etrogs being sold to unknowing Jews in the USA. Most of these came from etrog trees that had been grafted onto the rootbase of another citrus plant, like an orange, lemon or lime. Grafting is done with fruit trees to improve the viability of fruit trees: a plant with excellent fruit output is usually grafted onto a rootbase with excellent root strength.
While a very common practice among commercial fruit growers, this is a no-no among observant Jews. Fruits from etrog trees that have been grafted are NOT kosher and cannot be used to fulfill the requirements of the holiday of Sukkot. Be forewarned. A reputable grower will guarantee that his fruits do not come from grafted trees.
Also, a situation has arisen that has never happened before. In 2011, some enterprising souls in New York imported thousands of etrogs from Calabria and Israel well before the Sukkot holiday, before demand spiked the price of the fruit in the month prior to Yom Kippur. To keep the fruit from spoiling, they had the fruit irradiated, thus killing off parasites and pathogens living on and in the fruit, along with mold spores. Placing the fruit into refrigerators afterwards to store them, they then sold the etrogs months later to unsuspecting Jews at a large margin.
Irradiated etrogs are NOT kosher - the fruit is essentially dead after irradiation and dead etrogs cannot be used by observant Jews to fulfill the requirements of the holiday of Sukkot. You can usually tell if your etrog has been irradiated by sniffing the fruit. Irradiated etrogs do not emit that unique, lemon-like aroma, an aroma that is emitted by the living tissue in the peel, which becomes more intense as the Sukkot holiday progresses. This is because the peel is not living, but dead.
Update on Etrog Growing: Tips and Reminders
Etrog growing season is in full swing. The great heat we've been having in the Northeast is very conducive to Etrog trees, who love the heat here, as they do in Israel and Calabria. Here are some tips and reminders for those of you trying your hand at growing Etrogs.
1) In Connecticut, the most common problem is yellowing on the leaf perimeter; when it's bad, you'll see leaves with green veins and yellow in between: that's Iron deficiency (chlorosis). It shows up in the early spring, with the more mature leaves affected the most - acid-feeds will get rid of this problem and help with the trace mineral deficiencies that occur in parallel to iron deficiency. Feeding mixture: 2 tbsp. Rhododendron/Azalea food (Miracid) per 2-gallon watering can. Etrog trees are heavy feeders during the summer. Water first to soak the soil around your etrog (or the pot if yours are in pots), then top off on the soil around the plant with a feed mixture afterwards. Do this at least once a week up until early fall.
2) Etrog trees like a cool base during the night. Don't put your pots on blacktop or concrete - the heat during the day heats up the pots and the trees will seriously suffer. If you can't place your trees directly into the soil, place the pots on top of the ground (remove the water dish attached to the pot bottom to prevent pests from taking up residence in the empty space below the plants roots).
3) Part shade during the heat of the day. Etrog trees love full sun during the morning and afternoon; but during the heat of the day (noon), they like a bit of shade. I put mine in the noon shadow of some trees; during the mornings and afternoons they get full sun from the unshaded sides.
4) Growers in Calabria have told me that Aphids can be a problem for lots of citrus trees and especially for Etrogs. Ants feed on the honeydew made by the Aphids and will protect Aphids; ants are the primary vector for putting Aphids on your Etrog trees stems, branches and leaves. They look like small, brown or black, immobile bumps. They don't move around much, but stick suckers into the plant and suck out the juices. Aphids can literally coat every surface of an Etrog tree and suck the lifeblood out of the plant. They have to be killed or the plant will die.
I use a Bayer water-based insecticidal soap recommended for vegetables and fruits to kill the Aphids and the Ants. The Aphids, once killed, will remain on the stems and leaves because their suckers drill into the plant permanently - cleaning the plant of Aphid bodies will prevent mold and diseases from feeding on the dead Aphid bodies, and thus infecting the plant. So after spraying the Aphids, you *will* have to clean the stems and leaves of Aphids' bodies manually (they will come off using a paper napkin as a black and/or brown sludge). I find I have to spray and clean my etrog trees every two weeks in the Spring and early Summer. Until the trees get to be about 10 feet tall and develop bark, Aphids are a serious problem for Etrog trees grown in the Northeast and just about everywhere else.
5) Staking - Etrog trees tend to branch out and grow horizontally. If you want something more tree-like, you can trim the plant and support it so it grows skyward (fewer fruits on trees that are sometimes 25 feet or more tall) or support the long, horizontal branches with arbor devices like you use for beans and grape vines (trees that are 4 feet tall, but with 20 foot branches extending to the sides, which leads to many fruits). But staking and support are important in either case - Etrog stems and branches are pretty thin and break easily when the trees are younger. I use tomato sticks and plastic stakes I get at the garden store, along with velcro tomato tape to wrap and support the branches and attach them to the arbors, sticks and stakes.
6) Repotting - Etrogs tend to outgrow their pots quickly. In five years, expect to have to cut a barrel in half and repot your five-year-old tree in it. I use Miracle-Gro Moisture Control soil for my Etrogs - besides having Miracle-Grow in it, which I have to supplement with Miracid (Plant Food for Acid-Loving Plants), the moisture-control component keeps a more level moisture level in the pots.
7) Winter - Etrogs like indoor environments, with bright, indirect light, where it gets cooler at night. In our house, our Etrogs "sleep" in south-facing, 55 degree rooms, near the windows. Stop feeding during the winter, but continue to deep water once a week. Watch out for Aphids and Ant infestations, along with spider mites - use a water-based insecticidal soap and clean the stems, branches and leaves of dead insects afterwards.
8) Spring - Etrogs can take pretty cool temps, but I still hold off before I take mine out for good. I wait until the cotton-aster trees bloom and spread their cottony seeds around before I leave my Etrog trees outside for the season.
I have several more articles on etrog growing on this blog. Search under etrogs and-or advice - fruit horticulture to find them.
Etrogs Dropping Leaves - Help!
A common question coming in from all parts in the winter goes something like this: "Rabbi, I've watered correctly, I've fed correctly, my etrogs have just the right amount of sun, the temperature isn't too hot, nor too cool, yet my tree(s) are dropping leaves and dying like flies. What can I do?"
Answer: Etrogs are extremely sensitive to changes in humidity (as are most houseplants, too). Especially in the winter, where house humidity can vary 40% up and down in the same day. Etrog leaves, just like other plants' leaves, have microscopic openings that close and open during the day according to the humidity. If the humidity is too low, the openings close up and the plant essentially can't breath, and thus can't make food for itself, no matter how good the conditions are for growing otherwise. The dryer the air, the tighter the openings close. Essentially, dry air will asphyxiate your plant. The leaves that drop do so because they can't breath and have "run outa' air."
Smaller etrog plants have it harder than larger trees, since smaller plants have a higher metabolism and both make and burn up food faster. Larger plants have a slower metabolism and will be less affected by low humidity and humidity variations than smaller plants - but eventually even they can succumb to this, especially towards the end of the winter season as Spring approaches (humidity changes can really jump around during this period!). Coupled with those cold air downdrafts and low light conditions that often arise in the winter, etrog plants can be in serious pain during the winter in the Northeast.
Etrog plants pretty much have to have their local humidity in the area of 50% year round, without drastic changes. Winter household humidity changes in the Northeast US can be pretty severe, going from 20% to upwards of 40% and back down again every few hours as people enter and leave the environs. This can be very hard on a plant, since the opening and closing of these microscopic openings I spoke about isn't immediate, but can take hours to occur.
There is a way around this and you owe it to your etrogs to keep them healthy during this difficult season. Obtain clear plastic bags: either the clothing kind from the dry cleaner (tape up the hole for the hanger on the top) or vegetable bags from the grocery store. Make sure there are no rips in the bags. Use the larger bags to encase small-tree size etrog plants all the way to the sides of the container and the smaller grocery-size bags to encase smaller plants the same way. This will enable your etrogs to maintain a micro-environment around themselves with high humidity. Make sure the plants have bright, but indirect light. Bright direct light will cause your plants to broil in the bag because it will heat up in there.
For those plants that are tree size, you might as well rent space in a greenhouse or build your own.
Someone asked me about the sub-shoots growing off the side of the etrog central stalk. Here's the answer: etrog plants tend not to grow to great heights, btw, but stay about 4-5 feet high max. The long, horizontal shoots or branches growing off of a center stalk are pretty much the rule. In Calabria, where they grow these plants all the time for profit, the horizontal shoots are supported for several yards at about 4 feet off the ground using 2X4's - these horizontal branches are where the etrog fruits grow and are harvested. In Calabria, they don't have to worry about the humidity: it's always around a constant 50% or above there.
PS. The air holes I spoke about above are on the BOTTOM of the leaves - go ahead, look at them in a microscope. But it does help to lift the surrounding plastic bags off the plants and give them some "breathing room." Do so using chopsticks, shish-kabob or bamboo poles or whatever, matching the size of the poles to your container, creating a kind of tent around the plant. It may look funny and not exactly go with your decor, but the plants will better survive the winters here and be more vigorous when you let them out to play in the Spring. -- JS
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