ISD For Citrus Trees: Information On ISD Tags On Citrus

ISD For Citrus Trees: Information On ISD Tags On Citrus

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By: Darcy Larum, Landscape Designer

You’ve just purchased a lovely little lime tree (or other citrus tree). While planting it, you notice a tag stating “ISD Treated” with a date and also a treatment expiration date. The tag may also say “Retreat before Expiration.” This tag may leave you wondering, what is an ISD treatment and how to retreat your tree. This article will answer questions about ISD treatment on citrus trees.

What is an ISD Treatment?

ISD is an acronym for imidichloprid soil drench, which is a systemic insecticide for citrus trees. Citrus propagating nurseries in Florida are required by law to use an ISD treatment on citrus trees before selling them. ISD tags on citrus trees are put on to let the buyer know when the tree was treated and when the treatment expires. It’s recommended that the consumer treat the tree again before the expiration date.

While ISD treatment on citrus trees helps control aphids, whiteflies, citrus leaf miners and other common plant pests, its main purpose is to prevent the spread of HLB. Huanglongbing (HLB) is a bacterial disease affecting citrus trees that is spread by the Asian citrus psyllid. These psyllids can inject citrus trees with HLB while they feed on the leaves. HLB causes citrus foliage to turn yellow, fruit to not properly form or ripen, and eventually death to the whole tree.

Tips on ISD Treatment for Citrus Plants

The Asian citrus psyllid and HLB have been found in California, Florida, Texas, Louisiana, Alabama, Georgia, South Carolina, Arizona, Mississippi and Hawaii. Like Florida, many of these states are now requiring treatment of citrus trees to control the spread of HLB.

ISD for citrus trees usually expires about six months after they were treated. If you have purchased an ISD treated citrus tree, it is your responsibility to retreat the tree before the expiration date.

Bayer and Bonide make systemic insecticides specifically for treating citrus trees to prevent the spread of HLB by Asian citrus psyllids. These products can be purchased at garden centers, hardware stores or online.

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Read more about Citrus Trees

Citrus trees prefer their soil evenly moist and never soggy. Soil that stays too dry or too wet spells trouble. Commercial potting mixes labeled for cactus, palms and citrus provide a good balance of ingredients to retain moisture, yet drain freely and quickly. Mix in extra organic matter* with e arthworm castings to help keep nutrients available.

Homeowner Imidacloprid Recommendations for Edible Crops

Iowa State’s Plant and Insect Diagnostic Clinic has received several questions recently about the use of imidacloprid on apple trees and other edible fruits and vegetables. Imidacloprid is a systemic insecticide that has been available for many years under different trade names and concentrations. Systemic insecticides are taken up by the roots or other parts of the plant and then move internally through the plant tissues and kill insects eating those tissues. In contrast, non-systemic insecticides remain on the plant surface and kill insects by contact or ingestion of treated foliage.

Imidacloprid has been available to commercial growers for use on edible crops for over a decade. Homeowners, however, have not had any systemic insecticide available for insect control on fruits and vegetables until recently. A new product called Bayer Advanced Fruit, Citrus & Vegetable Insect Control is now available for the general public. It contains 0.235% imidacloprid. This product can only be applied to the soil.

In order to help you make decisions about using imidacloprid on edible food crops, we have compiled a list of the questions we are being asked. Remember, always read and follow label instructions when using any pesticide.

Does imidacloprid get into the fruits and flowers of plant?

Good question and not one that is easy to answer. Yes, it does get into the reproductive parts, but not in high enough concentrations to control pests. This is why if you use imidacloprid on your roses to control Japanese beetles it does not protect the flowers. Imidacloprid works best on pests that feed on leaves, stems, roots, or woody parts of the plant.

There is concern about how much imidacloprid gets into the nectar and pollen of plants and how this might affect pollinating insects. It is something to be aware of and why some labels say to not apply until after bloom. Imidacloprid is toxic to bees according to the imidacloprid fact sheet at Oregon State University’s National Pesticide Information Center. For this reason we favor an IPM-based pest management approach that reduces non-target effects by limiting insecticide applications to situations where other options are not available and using insecticides in a responsible manner.

What plants are listed on the label of Bayer Advanced Fruit, Citrus & Vegetable Insect Control?

There is a long list so check the label. Some examples plants likely to be grown in Iowa include:

  • Pome fruit such as apples and pear
  • Stone fruit such as apricot cherry, peach and plum
  • Strawberry, blueberry, raspberry, blackberry
  • Tree nuts such as walnut, chestnut, hickory
  • Many cucurbits including cucumber, pumpkin, muskmelon, squash, zucchini
  • Eggplants, peppers, tomatoes and some leafy vegetables
  • Many herbs

What insect pests are controlled by Bayer Advanced Fruit, Citrus & Vegetable Insect Control?

It depends on the crop being treated so check the label but in general it is labeled to control: aphids, leafhoppers, whiteflies, mealybugs, spittlebugs, cucumber beetles, some thrips, Colorado potato beetles, and flea beetles.

What apple pests present in Iowa are listed on the Bayer Advanced Fruit, Citrus & Vegetable Insect Control label?

It controls aphids (including woolly apple aphid) and leafhoppers, both of which are generally not a problem for homeowners growing apples in Iowa.

Are apple maggot and codling moth listed as target insects for Bayer Advanced Fruit, Citrus & Vegetable Insect Control?

No, these fruit-infesting pests are not on the label and it will not provide control. The imidacloprid will not be present in the fruit in high enough concentrations to control these pests.

Will Bayer Advanced Fruit, Citrus & Vegetable Insect Control prevent Japanese beetle damage?

This product controls Japanese beetles on only bushberry plants (e.g., blueberry, current, elderberry, huckleberry, Juneberry, Ligonberry, Salal). It will not control Japanese beetles on other plants.

So, why can I use imidacloprid on other plants to control Japanese beetles?

Other products have a much higher rate of the active ingredient imidacloprid (1-3%) AND it is labeled for use on ornamental trees and shrubs, not plants with edible parts.

A different product, Bayer Advanced 12-month Tree & Shrub Insect Control Super Concentrate with 2.94% imidacloprid, controls Japanese beetles and lists apple trees on the label. Why can’t I use this?

This is confusing but in general any pesticide being used on any fruit, vegetable or other plant with edible parts will have information on pre-harvest intervals (the number of days from treatment until the plants can be harvested). This information is absent on the Bayer Advanced 12-month Tree and Shrub Insect Control label. We advise you not use this product for apple trees.

Further, we advise that if homeowners want to use a product with imidacloprid as the active ingredient that they use one specifically labeled for edible food crops. The product label will contain specific instructions on application, pre-harvest intervals, and special instructions on limiting harm to pollinators.

In Iowa what crop/pests will Bayer Advanced Fruit, Citrus & Vegetable Insect Control be most useful for?

Cucumber beetles that vector bacterial wilt on cucurbits. Other potential uses in Iowa are for managing whiteflies on tomatoes, flea beetles on tomato and eggplant, and leafhoppers on beans and peas.

When can I eat the fruit and vegetables treated with Bayer Advanced Fruit, Citrus & Vegetable Insect Control?

It is normal for Meyer lemon trees to go through a period of shock after moving into a new location. A lot of leaves can drop and the plant will recover. Just be sure not to over water it in hopes that the leaves will stop dropping.

The fruit will drop off at a very small stage if the flowers are not pollinated. If the plants are outside during flowering, they will be pollinated naturally by insects. Inside the home, you can pollinate them by hand with a cotton swab. Gently rub one end of the swab around each newly opened flower. You will see yellow pollen on the tip of the swab. The flowers are pollinated by transferring the pollen from flower to flower with the cotton swab. There is a sticky substance naturally at the tip of the female part of the flower (stigma).

My Meyer lemon has a lot of sticky residue on the leaves this time of year. Scale insects exude honeydew. Scale are very hard to see. I remove as many as possible by gently rubbing the upper and lower mid veins of the leaves with a cotton swab dipped in alcohol. Scale are controlled naturally by beneficial predators when outside.

I don't know what the treatment is you referred to above. But I would not advise using a systemic pesticide as it can kill beneficial insects.

BTW, it takes many months for the lemons to mature. Be patient!

Unlike roots that spread freely through the garden to absorb water and nutrients, containerized roots are at your mercy for food and drink. Citrus trees in containers are particular about water, which is also essential for fruit development. Provide consistent soil moisture, keeping it just a bit on the dry side. However, don't allow roots to dry out completely. Consistently wet soil is bad news because citrus are susceptible to root rot.

"How often do I water?" must be the most frequently asked question in gardening. "It depends" is the most accurate, although frustrating, answer. Water use depends on many interrelated factors, such as soil type, plant size, pot type, growing season, weather (sun, wind, rain) and if the pot is inside or outside. Be careful about accepting watering "rules" that may not be applicable to your conditions. Your best bet is to monitor soil moisture regularly. Follow a consistent schedule, watering as infrequently as possible, but allowing water to soak through the root zone and out the drainage holes each time. Make sure the pot sits above any salty drainage water, so it won't be reabsorbed and damage roots.

Test the soil moisture levels in the root zone. Use an inexpensive soil moisture meter or make a low-tech version from a wooden chopstick. Push it into the soil, pull it out, "feel" if it is dry or moist, or observe if moist soil sticks to it. Keep a simple journal of water use through the seasons to help you fine-tune and understand your citrus tree's requirements. If won't be long before you just know when it's time to water.

Feed containerized citrus regularly with a complete fertilizer, containing nitrogen, phosphorous and potassium (NPK), as well as other macronutrients and micronutrients, including iron, magnesium, manganese and zinc. Citrus fertilizers are an easy option as they contain the extra nitrogen and micronutrients the plants need to thrive. Complete all-purpose fertilizers can also do the trick if you supplement with an occasional foliar spray of a nitrogen-rich fertilizer that contains micronutrients.

Follow package instructions for amounts and frequencies. As a general guideline, apply fertilizer just as new growth starts in late winter/early spring and continue through the prime growing season into late summer/early fall. Citrus trees don't go completely dormant, so you may continue feeding after you move them indoors, although you may choose to dilute the dosage by half. Most gardeners who leave citrus pots outdoors all year stop feeding in late summer/early fall because tender new growth is susceptible to frost damage.

Recognizing and Managing Lemon Tree Disease

Prized for their mouth-puckering, sunny-hued fruit and hauntingly fragrant white blooms, lemon trees (Citrus limon) are an iconic part of tropical and Mediterranean landscapes from Florida to California. With enough TLC, a single lemon tree can supply an entire household with a lifetime of lemonade. And a big part of caring for a lemon tree is in learning to recognize and manage outbreaks of these diseases.

Stopping Disease before It Starts

Diseases will be few and far between, as long as you provide your tree with:

  • Well draining soil or potting mix. Soggy soil invites root disease.
  • Eight or more hours of daily sun. This usually isn’t a problem where lemon trees grow outdoors in USDA plant hardiness zones 9 through 11. Put indoor trees in colder areas near a large south-facing windows.
  • Frost protection and shelter from hot, drying winds. Keep an indoor tree away from cold drafts and heating vents.
  • Regular watering a first-year tree two to three times weekly. Water an established one deeply and slowly once a week unless it rains. Water an indoor lemon when the potting mix feels very dry.
  • Regular applications of citrus fertilizer and trace minerals, starting when a young tree puts out its first new leaves.

Major Lemon Tree Diseases

Three of the four diseases most threatening to lemon trees are easily managed, but the fourth is deadly.


Sap-sucking aphids transmit the tristeza fungus to lemon trees as they feed. Tristeza symptoms include:

  • Stunted growth
  • Declining fruit production
  • Yellowing leaves

Untreated trees often succumb to root rot. Check you trees daily for aphid colonies feeding on the leaves and new shoots. Saturate it with organic insecticidal soap at the first sign of an aphid infestation.

Foot Rot

Branches dying back, bark peeling at the soil line and black gum oozing from the lower trunk indicate a foot rot infection. Soggy roots are the culprits well draining soil is the solution. Keeping mulch away from the trunk also helps.

Citrus Canker

Windy weather and unsanitary tools spread citrus canker. It surfaces as corky, yellow-margined spots on the new leaves and twigs. A severely infected lemon tree may temporarily defoliate. To prevent infection, apply organic copper fungicide spray with each flush of new growth.

Citrus Greening

Aphid-related citrus psyllids transmit this incurable condition. Deformed fruit, branch dieback and yellow-mottled leaves follow. An infected lemon tree serves as a reservoir of the greening bacteria. It must be completely removed, bagged and destroyed — including the entire root system.

Watch the video: Caring for Citrus Trees in Texas. Big Tex Urban Farms