Finishing Bedding Plants and Perennials
Now that the 2003 spring season is behind us, it’s time torecap problem areas. Working with my clients and traveling around the UnitedStates giving talks, I can narrow down the number of areas that need work tofive. There are obviously more cultural problems that need attention, but mytop five encompass the growers’ greatest concerns. These top issues are where Ispend most of my time with clients.
Insects and Diseases
Growers seem to be battling insects and diseases every year,regardless of how many newer and better chemicals come onto the market. Forinsects, it boils down to scouting, sticky cards, sanitation, using the rightchemicals and getting good chemical distribution during application. I have ahard time convincing growers to stay up on their use of sticky cards andscouting.
Thrips continues to be the number-one insect problem. Yellowand blue sticky cards placed two inches above crops are the first line ofdefense. Put sticky cards in basket lines as well, since thrips will probablyshow up there first. Use sticky cards to determine where you have thrips andhow well your chemical applications are working. Sticky cards will also workwell with whiteflies, fungus gnats and shoreflies. For all other insects, youneed to scout susceptible crops on a weekly basis.
Fungus gnats and shoreflies have long been considered simplynuisances but are now being recognized as pests worthy of control. Adults ofboth pests can spread various root and crown rot diseases. Larvae of fungusgnats can feed on tender roots of many crops, especially poinsettias, cyclamenand Easter lilies. Control of these two pests can be difficult, as they likemoist conditions with algae and decaying organic matter to feed on. Use thedown time between crops to treat floors for larvae and pupae, using Adept,Distance, lime, rock salt, Hypoaspis mites or Atheta beetles. Best control isby sprenching or drenching to eliminate larvae within the crops, followed byULV or autofog applications for adults. More growers are turning tobiocontrols.
Control of whiteflies and aphids has generally been withMarathon drenches on susceptible crops, especially baskets and large pots. Ifnot using Marathon as a preventative, plan on weekly sprays based on scouting.It is really embarrassing when your shipping people or your customers tell youthat you have whiteflies or aphids.
Disease control must be based on moisture and humidity management,scouting, correct identification of disease, sanitation, weed control and closeexamination of all plant material brought into the greenhouse. I emphasize toevery grower that they need disease identification books at their fingertipsand a good diagnostic lab where they can get a quick, accurate diagnosis. Wetgrowing conditions, growing on the ground, poorly draining media and no airmovement are great for root and crown rots, Botrytis and many other diseases.Make sure leaves are dry at night by using a dehumidification cycle at day’send, watering only in the a.m., having good air movement and keeping plantsfrom overgrowing or growing pot-tight. Keep dead flowers from falling offbaskets onto the crop below. Rogue out any diseased plants, and spray the restfor protection. Avoid reusing containers without proper disinfection, keepweeds out of the greenhouse and clean up after shipping or moving plants.
Make sure to rotate Subdue with Truban or Terrazole, as wellas Aliette, for control of warm-weather Pythium and Phytophthora withoutresistance. Botrytis will always be a problem when the weather is wet and thegreenhouse is full. Spray for Botrytis before the wet weather starts to getprotection, as you will not be watering during the wet weather. Use Decree(with Capsil), Medallion or a low rate of Phyton 27 when flowers are showing,and Daconil, Chipco 26GT and Heritage when plants are green. Downy mildewcauses great headaches on the West Coast during the rainy season, affectingalyssum, pansy, stock and especially snapdragons. In Florida, there is a downymildew that attacks Salvia splendens only. For handling fungal and bacterialleafspots, you must know what you are dealing with before you can spray, as noone chemical controls all of those leafspots. Á Viruses can cause lateand serious problems on certain crops, not showing symptoms until plants areunder stress or starting to flower. Send any suspicious samples for diagnosis.
Figure 1, starting on page 122, contains a list of recommendedfungicides and insecticides. These chemicals are working for growers, but thereare more chemicals labeled than what is on this list. For pests such as thrips,rotate after two applications of a chemical, and use three different chemicalclasses and modes of action. For mites, rotate with each application. Remember,the more often you spray for a pest, the more you need to rotate. Use autofog,ULV or other types of foggers to get better chemical distribution, especiallyif you produce a lot of hanging baskets. Sprays can also be effective, but youmust get coverage under the leaves. For Botrytis, make sure to rotate with eachapplication. Use monthly drenches for root and crown rots. More growers areturning to biocontrols such as Rootshield and Companion for control of root andcrown rots. With most diseases, protective spraying should be practiced onsusceptible crops and when the weather is conducive for disease spread.Virus-infected plants can only be dumped.
Cutting quality and Florel
With more and more vegetative annuals being produced,growers are becoming more reliant on unrooted and rooted cuttings. Almost allof these cuttings come from off-shore locations selected for proper environmentand cheap labor. However, these locations can also have problems with workertraining, insects and diseases, water quality, shipping and order fulfillment.Transferring to rooted cuttings will not alleviate the problem, as the unrootedcuttings that the rooting stations use come from off-shore locations.
The biggest problems I see with cuttings are lack of uniformstandards (size of cuttings, number of nodes, etc.), disease problems, gassingof cuttings when insects are found, shipping time, temperature control andpinching of rooted cuttings. The image above shows three different size plantsof ‘Freedom Red’ poinsettias grown from a rooted cutting in the same greenhousewith the same culture. What causes the difference in finish size is the sourceof the rooted cutting. Small, thin cuttings will have less vigor and requireless growth regulators to finish. Recent problems with diseases, such asRalstonia and TMV, reinforces the problem with imported cuttings.
An area I think needs more attention is the use of Florel oncuttings during propagation. I published an extensive article on Florel in theOctober 2002 issue of GPN. Florel used on cuttings after they start to rootwill increase branching with or without pinching, will cause disbudding ordelay flowering in many crops, and will control early stretch. Rooting stationscould use Florel before they ship the rooted cuttings to other growers, whowould then benefit from the greater branching whether they used Florel again ornot. For best results with Florel, ensure water pH in the spray tank is lessthan 5.0 after adding Florel, spray to run-off, avoid spraying plants understress and keep leaves moist for 3-4 hours. Use Florel around the time youwould pinch, and determine how long your reblooming time will be for each crop.For geraniums and summer torenia, it may be 6-7 weeks, while other crops willonly be delayed 2-4 weeks.
Flowering times
Growers in many parts of the country are being asked to haveperennials and many annuals in flower well before their natural season. This isespecially true in California, Arizona and the Southeast. Perennials are beingscheduled to flower the first year and sold at the same time as bedding plantsin the Midwest. Wave petunias need to be in flower in February and March in thewarmer parts of the country. However, varieties such as ‘Purple Wave’ need longdays to flower and are not receptive to photoperiod until five leaves areexpanded. This means growers must light plugs and liners to get crops such asPurple Wave to flower earlier. Other long-day annuals include lobelia, otherpetunias, Salvia farinacea, some pansies, ageratum, some portulaca, somesnapdragons and tuberous begonia. On the other hand, I see growers havingproblems with short-day plants such as cosmos flowering too fast and being tooshort early in the season, but then growing too tall while waiting for flowerslater in spring. The same problem can happen with Zinnia elegans and Africanmarigolds.
I see more and more growers lighting plugs and liners forphotoperiod than ever before. (See page 32 for more information on lighting.)Even plug producers in Southern California and Florida are lighting certaincrops to provide a faster flowering plug for some customers. We are finding outthat certain vegetative annuals are also long-day flowering and should be litin the propagation stage or shortly after potting.
To get perennials to flower on time in the spring, growersmust use vernalization, photoperiod or a combination of both, depending on thecrop. Seed companies are offering first-year flowering varieties. The bigquestion is — What does your customer want?
Growth Regulators
This is probably the number-one topic I cover with myclients! It’s not just a matter of which growth regulator to use on which crop,but what method of application is best. Growers are learning about thedifferences between sprays, sprenches and drenches. I wrote an extensivearticle on growth regulators in the March 2003 issue of GPN, complete withstarting rates for sprays and drenches. I think all growers are familiar withsprays, but uniformity is still difficult with Bonzi and Sumagic. Tank mixesare being used more often. Most common is B-Nine + Cycocel, but some growersare using B-Nine + A-Rest (especially on fall pansies) and B-Nine + Bonzi orSumagic. You can get more activity from tank mixes than either chemical alone.Tank mixes are especially useful on perennials.
Plug growers everywhere are learning how to do sprenchesearly in a crop to keep it from stretching. You can use A-Rest, Bonzi or Sumagic,as all of these chemicals are active in the soil through the roots. By usingthis early sprench, you will have to do fewer sprays later on. Crops mostlikely to be sprenched early include cosmos, zinnia, marigold, snaps, celosia,dianthus, dahlia, pansy, impatiens and even Salvia splendens.
Most growers are, however, using drenches, either early orlate in the crop. The image on page 116 shows impatiens baskets that haverecently been drenched with Bonzi, allowing the plants to continue to flower butnot to stretch. Drenches are typically applied when plants are up to saleablesize and starting to bud or flower. A late drench of A-Rest, Bonzi or Sumagicwill not delay flowering, but a late spray may. Containers need to be moistbefore drenching, and large containers such as hanging baskets should have aknown volume of chemical applied per container. This can be done through anEcho system, Chemdoser (Dramm), portable injector and counting or by cup. However,to drench 4-inch pots and flats, you need to apply the growth regulator likeyou are feeding, making sure to get 10-percent run-through. This is easily donethrough portable injectors.
Once you get the hang of applying drenches, you start doingan earlier drench rather than a spray. Reasons for this include the length ofcontrol and no overspray onto sensitive crops. Remember, a drench should allowthe plant to grow out in 2-3 weeks. If not growing out, you applied too muchchemical. Get out the Pro-Gibb and spray at 3-5 ppm or feed with more NH4fertilizer. If not holding for at least one week, you applied too littlechemical. Either increase the ppm used or the volume applied.
A new technique being worked out is a liner dip, where thevegetative liner is dipped in A-Rest, Bonzi or Sumagic before being potted.This should control growth for 2-3 weeks. A final drench may still be needed in4- to 6-inch pots. Liner dips will work best in combinations where you havevigorous and non-vigorous varieties growing together. Sprays and drenches areimpractical on many combos, as you will overcontrol the non-vigorous varieties.
Combinations
This is the area in the market with the most growthpotential, but one which is getting abused by poor selections and shipping.Combinations can come in many sizes and shapes, with the most attractive beingdone in large containers. This product allows you to manipulate shapes, colorsand textures to produce a combo that will thrive all season. Design combos forsun and shade. Look into the latest color trends. Get good ideas for combosfrom cuttings and seed suppliers, as well as books, magazine articles and yourworkforce. Develop a menu of combos, and offer to customize.
The biggest problem is not what combos to put together, buthow to control them once put together. Wholesale growers have this problem withthe big box stores. You cannot let combos get too big or they won’t ship. Sincemost combos are put together early with liners and plugs, you need tounderstand which plants need controlling and which do not. Use Florel, pinchesand liner dips for vigorous varieties before putting into the combo. Somecombos can still be drenched at the end with A-Rest, Bonzi or Sumagic, but makesure there are no slow-growing varieties in that combo. Design carts or racksthat can deliver containers in one piece.
Well, there you have it, my top five issues for this pastspring. I imagine many of you can relate to these five items. And probably nextspring, I will still be spending most of my time on these issues, as will you.Here’s hoping we keep learning every year and making fewer mistakes!
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