Now that the 2003 spring season is behind us, it's time to
recap problem areas. Working with my clients and traveling around the United
States giving talks, I can narrow down the number of areas that need work to
five. There are obviously more cultural problems that need attention, but my
top five encompass the growers' greatest concerns. These top issues are where I
spend most of my time with clients.
Growers seem to be battling insects and diseases every year,
regardless of how many newer and better chemicals come onto the market. For
insects, it boils down to scouting, sticky cards, sanitation, using the right
chemicals and getting good chemical distribution during application. I have a
hard time convincing growers to stay up on their use of sticky cards and
Thrips continues to be the number-one insect problem. Yellow
and blue sticky cards placed two inches above crops are the first line of
defense. Put sticky cards in basket lines as well, since thrips will probably
show up there first. Use sticky cards to determine where you have thrips and
how well your chemical applications are working. Sticky cards will also work
well with whiteflies, fungus gnats and shoreflies. For all other insects, you
need to scout susceptible crops on a weekly basis.
Fungus gnats and shoreflies have long been considered simply
nuisances but are now being recognized as pests worthy of control. Adults of
both pests can spread various root and crown rot diseases. Larvae of fungus
gnats can feed on tender roots of many crops, especially poinsettias, cyclamen
and Easter lilies. Control of these two pests can be difficult, as they like
moist conditions with algae and decaying organic matter to feed on. Use the
down time between crops to treat floors for larvae and pupae, using Adept,
Distance, lime, rock salt, Hypoaspis mites or Atheta beetles. Best control is
by sprenching or drenching to eliminate larvae within the crops, followed by
ULV or autofog applications for adults. More growers are turning to
Control of whiteflies and aphids has generally been with
Marathon drenches on susceptible crops, especially baskets and large pots. If
not using Marathon as a preventative, plan on weekly sprays based on scouting.
It is really embarrassing when your shipping people or your customers tell you
that you have whiteflies or aphids.
Disease control must be based on moisture and humidity management,
scouting, correct identification of disease, sanitation, weed control and close
examination of all plant material brought into the greenhouse. I emphasize to
every grower that they need disease identification books at their fingertips
and a good diagnostic lab where they can get a quick, accurate diagnosis. Wet
growing conditions, growing on the ground, poorly draining media and no air
movement 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's
end, watering only in the a.m., having good air movement and keeping plants
from overgrowing or growing pot-tight. Keep dead flowers from falling off
baskets onto the crop below. Rogue out any diseased plants, and spray the rest
for protection. Avoid reusing containers without proper disinfection, keep
weeds out of the greenhouse and clean up after shipping or moving plants.
Make sure to rotate Subdue with Truban or Terrazole, as well
as Aliette, for control of warm-weather Pythium and Phytophthora without
resistance. Botrytis will always be a problem when the weather is wet and the
greenhouse is full. Spray for Botrytis before the wet weather starts to get
protection, 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 mildew
causes great headaches on the West Coast during the rainy season, affecting
alyssum, pansy, stock and especially snapdragons. In Florida, there is a downy
mildew that attacks Salvia splendens only. For handling fungal and bacterial
leafspots, you must know what you are dealing with before you can spray, as no
one chemical controls all of those leafspots. Á Viruses can cause late
and serious problems on certain crops, not showing symptoms until plants are
under stress or starting to flower. Send any suspicious samples for diagnosis.
Figure 1, starting on page 122, contains a list of recommended
fungicides and insecticides. These chemicals are working for growers, but there
are 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 chemical
classes 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, especially
if you produce a lot of hanging baskets. Sprays can also be effective, but you
must get coverage under the leaves. For Botrytis, make sure to rotate with each
application. Use monthly drenches for root and crown rots. More growers are
turning to biocontrols such as Rootshield and Companion for control of root and
crown rots. With most diseases, protective spraying should be practiced on
susceptible crops and when the weather is conducive for disease spread.
Virus-infected plants can only be dumped.
With more and more vegetative annuals being produced,
growers are becoming more reliant on unrooted and rooted cuttings. Almost all
of these cuttings come from off-shore locations selected for proper environment
and cheap labor. However, these locations can also have problems with worker
training, insects and diseases, water quality, shipping and order fulfillment.
Transferring to rooted cuttings will not alleviate the problem, as the unrooted
cuttings that the rooting stations use come from off-shore locations.
The biggest problems I see with cuttings are lack of uniform
standards (size of cuttings, number of nodes, etc.), disease problems, gassing
of cuttings when insects are found, shipping time, temperature control and
pinching of rooted cuttings. The image above shows three different size plants
of 'Freedom Red' poinsettias grown from a rooted cutting in the same greenhouse
with the same culture. What causes the difference in finish size is the source
of the rooted cutting. Small, thin cuttings will have less vigor and require
less growth regulators to finish. Recent problems with diseases, such as
Ralstonia and TMV, reinforces the problem with imported cuttings.
An area I think needs more attention is the use of Florel on
cuttings during propagation. I published an extensive article on Florel in the
October 2002 issue of GPN. Florel used on cuttings after they start to root
will increase branching with or without pinching, will cause disbudding or
delay flowering in many crops, and will control early stretch. Rooting stations
could use Florel before they ship the rooted cuttings to other growers, who
would then benefit from the greater branching whether they used Florel again or
not. For best results with Florel, ensure water pH in the spray tank is less
than 5.0 after adding Florel, spray to run-off, avoid spraying plants under
stress and keep leaves moist for 3-4 hours. Use Florel around the time you
would 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 will
only be delayed 2-4 weeks.
Growers in many parts of the country are being asked to have
perennials and many annuals in flower well before their natural season. This is
especially true in California, Arizona and the Southeast. Perennials are being
scheduled to flower the first year and sold at the same time as bedding plants
in the Midwest. Wave petunias need to be in flower in February and March in the
warmer parts of the country. However, varieties such as 'Purple Wave' need long
days to flower and are not receptive to photoperiod until five leaves are
expanded. This means growers must light plugs and liners to get crops such as
Purple Wave to flower earlier. Other long-day annuals include lobelia, other
petunias, Salvia farinacea, some pansies, ageratum, some portulaca, some
snapdragons and tuberous begonia. On the other hand, I see growers having
problems with short-day plants such as cosmos flowering too fast and being too
short early in the season, but then growing too tall while waiting for flowers
later in spring. The same problem can happen with Zinnia elegans and African
I see more and more growers lighting plugs and liners for
photoperiod than ever before. (See page 32 for more information on lighting.)
Even plug producers in Southern California and Florida are lighting certain
crops to provide a faster flowering plug for some customers. We are finding out
that certain vegetative annuals are also long-day flowering and should be lit
in the propagation stage or shortly after potting.
To get perennials to flower on time in the spring, growers
must use vernalization, photoperiod or a combination of both, depending on the
crop. Seed companies are offering first-year flowering varieties. The big
question is -- What does your customer want?
This is probably the number-one topic I cover with my
clients! 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 the
differences between sprays, sprenches and drenches. I wrote an extensive
article on growth regulators in the March 2003 issue of GPN, complete with
starting rates for sprays and drenches. I think all growers are familiar with
sprays, but uniformity is still difficult with Bonzi and Sumagic. Tank mixes
are being used more often. Most common is B-Nine + Cycocel, but some growers
are using B-Nine + A-Rest (especially on fall pansies) and B-Nine + Bonzi or
Sumagic. 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 sprenches
early 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 using
this early sprench, you will have to do fewer sprays later on. Crops most
likely 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 or
late in the crop. The image on page 116 shows impatiens baskets that have
recently been drenched with Bonzi, allowing the plants to continue to flower but
not to stretch. Drenches are typically applied when plants are up to saleable
size and starting to bud or flower. A late drench of A-Rest, Bonzi or Sumagic
will not delay flowering, but a late spray may. Containers need to be moist
before drenching, and large containers such as hanging baskets should have a
known volume of chemical applied per container. This can be done through an
Echo 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 like
you are feeding, making sure to get 10-percent run-through. This is easily done
through portable injectors.
Once you get the hang of applying drenches, you start doing
an earlier drench rather than a spray. Reasons for this include the length of
control and no overspray onto sensitive crops. Remember, a drench should allow
the plant to grow out in 2-3 weeks. If not growing out, you applied too much
chemical. Get out the Pro-Gibb and spray at 3-5 ppm or feed with more NH4
fertilizer. If not holding for at least one week, you applied too little
chemical. Either increase the ppm used or the volume applied.
A new technique being worked out is a liner dip, where the
vegetative 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 in
4- to 6-inch pots. Liner dips will work best in combinations where you have
vigorous and non-vigorous varieties growing together. Sprays and drenches are
impractical on many combos, as you will overcontrol the non-vigorous varieties.
This is the area in the market with the most growth
potential, but one which is getting abused by poor selections and shipping.
Combinations can come in many sizes and shapes, with the most attractive being
done in large containers. This product allows you to manipulate shapes, colors
and textures to produce a combo that will thrive all season. Design combos for
sun and shade. Look into the latest color trends. Get good ideas for combos
from cuttings and seed suppliers, as well as books, magazine articles and your
workforce. Develop a menu of combos, and offer to customize.
The biggest problem is not what combos to put together, but
how to control them once put together. Wholesale growers have this problem with
the big box stores. You cannot let combos get too big or they won't ship. Since
most combos are put together early with liners and plugs, you need to
understand which plants need controlling and which do not. Use Florel, pinches
and liner dips for vigorous varieties before putting into the combo. Some
combos can still be drenched at the end with A-Rest, Bonzi or Sumagic, but make
sure there are no slow-growing varieties in that combo. Design carts or racks
that can deliver containers in one piece.
Well, there you have it, my top five issues for this past
spring. I imagine many of you can relate to these five items. And probably next
spring, 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! style="mso-spacerun: yes">
With spring over, it's time to look back at this year's top five production problems.