Summer Xeriscaping Series: Part 5 of 9

Welcome back to another somewhat belated episode of Lost in the Farmer’s Market, as you may know the entirety of the months of July and August are devoted to the Summer Xeriscaping series and to day will be the fifth installment. In addition to the main feature is an included mini-article about a useful garden topic that relates to current goings on in the test gardens and or seasonal topics to help you produce more with less cost.  This week’s mini-article is about handling severe crop damage.

Generally when a pest of one sort or another begins to damage your preferred crops you have to determine when to take action, this process is called an ‘Action Threshold’. By definition an action threshold is a series of points that determine when to take action and what action to take. Not always is a pest problem worth doing anything about some times these pests are handled by nature itself. A good example of a problem that requires no action is when a tomato horn worm is found, but is covered with cocooned wasp larvae. In this case no action needed, another example is to see you have an aphid problem but a lot of them are dead, dark colored and have circular holes in their abdomens, again the problem is being handled by nature and thus no action needed.  Now take the problem currently on going in the test gardens. Since spring there has been an ongoing whitefly problem, normally these pests would simply not be a problem; I wouldn’t even waste the time to use insecticides. But they started to damage the nightshade crops seemingly favoring the eggplants first then the tomatoes. This is where the action thresholds I mentioned before come in; until the food output started to suffer I had planned to do nothing. As the white fly fed they damaged the plants, produced honey dew and that brought in fire ants, and on that spilled honey dew sooty mold began to kill off the leaves. When severe defoliation results, it then becomes an issue of the final threshold being reached, at this point little can be done and thus there are two options.  Option one is to allow the plants to fail and don’t bother to replant.  Option two is to cut down all effected plants dispose of any possibly contaminated soil if the plants were in pots, let the areas sit empty for a week and then replace all plant material and hope for a fall crop.  The difference is based on how determined you are and what sort of garden you have. Replanting for a late summer or early fall crop is not a big deal in fact cutting your losses can some times provide a better overall result even if you see some gardening downtime.

 In this case as you can see I had to cut down the worst affected plants in order to have a chance at a later harvest. The next step here is to treat all  remaining plants with systemic pesticide.

 In the case of potted plants all the effected plants have been cut down and the potting soil disposed of to prevent any new infestations due to eggs in the soil. Shortly after this picture was taken the pots were washed out, allowed to dry and a few days later refilled with new soil enriched with black hen.

Eucalyptus cinerea – Eucalyptus 7-11

Eucalyptus follows it's own rules when it comes to form and shape if you want the best oil content harvest new growth.

Eucalyptus up north is considered an annual unless grown as a houseplant during the winter. In southern areas like USDA zone 7 and southward Eucalyptus is a perennial.  It is important to note that Eucalyptus starts out as a somewhat loose shrub with a naturally weeping habit.  Given time Eucalyptus can develop into a thirty foot tall tree with a loose habit and especially attractive bark.  When mature the flowers of Eucalyptus are quite a stunning sight being fluffy in appearance and typically white in color. That said Eucalyptus produces large amounts of nectar that Honey bees can harvest to add a unique flavor to honey itself. Additionally the essential oils of Eucalyptus are quite effective as a decongestant and are used most notably in varied cough syrups and lozenges.  When used for garden purposes Eucalyptus is best used as a roughly horizontal centerpiece. The foliage is grey-silver in color and is quite effective in breaking up rough straight lines or providing loose foliage for informal barriers. I do have to note that Eucalyptus is a very slow growing perennial and may take decades to get to full size but with careful pruning you can keep it a reasonably neat shrub  and of course have little shortage of aromatic eucalyptus boughs for your home.

Echinacea purpurea 'Magnus'  – Purple Coneflower

Echinacea purpurea – Purple Coneflower

The coneflowers are members of the aster family and are best known in the trade as a group of durable summer-blooming perennials with deer resistance and excellent drought tolerance. Admittedly Coneflowers have become incredibly popular in the last decade with both the rise of Xeriscaping and organic gardening, as a result of this numerous cultivars now exist with previously unthought-of colors beyond the traditional purple (E. purpurea). If you add in the varied medicinal and ornamental forms of coneflower like those listed below you get a much wider range of color.

Echinacea angustifolia – Narrow Leaf Coneflower (pale purple)

Echinacea pallida – Pale Purple Coneflower

Echinacea paradoxa – Yellow Coneflower

Echinacea sanguinea – Sanguine  Coneflower (Red-Purple)

Echinacea tennesseensis – Tennessee Coneflower (Lavender-Purple)

Most if not all coneflowers being native have good tolerance for the natural weather of the continental united states which makes it an excellent choice for any good Xeriscaping design. When considered in conjunction with vinca and Eucalyptus  the coneflowers make an excellent tall color and foliage accent for the bed around the base of a eucalyptus tree. If one considers the variations in bloom color that include purple, red, pink, lavender yellow, orange and white the possibilities for use as a color-support perennial are virtually limitless.

Catharanthus rosea – Madagascar periwinkle

Madagascar Periwinkle is one of those annuals that comes in a great variety of bloom colors yet despite this it tends not to steal the show as does other more popular annuals such as petunias or million bells.

Madagascar periwinkle is one of those annuals that is sold country wide as a drought and deer-tolerant bedding annual. Madagascar periwinkle is often commonly called ‘vinca’ in the nursery trade due to its casual resemblance to the perennial ground-cover known as vinca.  Vinca the annual bedding plant is not actually related to the perennial ground cover but it’s ability to effectively block out weeds with dense green foliage and produce a attractive flower once mature.  The key to annual vinca’s drought tolerance can be found in the features that also make is undesirable for browsing. The waxy leaves and stems produce a white latex sap when damaged which both acts as a repellant for creatures wanting to eat it but also serves to reduce water loss during times of drought. When paired with a similar plant such as Eucalyptus the vinca can be used to form a low border to keep the weeds down. Additionally the green foliage is similar in shape but can be planted in contrast to the Eucalytus’s silvery coloration. For note  Madagascar periwinkle is also known under additional Latin names Vinca rosea, Ammocallis rosea, and Lochnera rosea.

Hopefully your harvest thus far has not suffered the same insect maladies mine have in the test garden, but even if it has I do have a few pointers as a final thought.

1. Always identify the actual problem and treat that as opposed to treating the secondary issues. 

 (ie the white fly are the main problem the sooty mold and fire ants are secondary)

2. Try to use non-chemical methods first and in the right proportions.

(In treating white fly I first used Neem Oil and to reduce the sooty mold cotton swabs soaked in rubbing alcohol, lastly I used diatomaceous earth to counter the fire ants.)

3.  If all other options are exhausted use limited amounts of chemicals but make sure you know the side effects of the active ingredients.

(for example Imidicloprid a common systemic insecticide can have negative impact on honeybees and, Malathion can kill honey bees if they come into contact with the spray. Both have absolute application limits which must be heeded as well as time limits after application to harvesting.)

The next episode of Lost In The Farmer's Market will continue the Xeriscaping series, where we will be covering two xeriscaping shrubs and a durable perennial all of which are quite dramatic in color and use. Also  our sub topic will be 'The science of productive container gardening' which is all about producing food in limited space despite droughts.  

Thank you again for reading and as always folks keep 'em growing!