Hello Cecilia,

Thank you for the pictures; it would help us to be able to see the symptoms in a bit more detail, though, if you are able to take clear close-ups of the odd growths and attach them to your reply. Of particular interest are the leaf undersides (such as the one in your current photo) and the fruit with visible residue/scarring. We cannot quite determine what is causing the plant's symptoms from these images.

Additional information would help us narrow-down possible causes:

• where has the plant been grown, and for approximately how long? (was it inside all winter? is it outside now or has it been outside for some time? have you had it for several years? what kind of container is it in - are there drain holes in the bottom?)
• does the whitish growth we see on the leaf underside and on the developing fruit rub off when touched, and is it powdery, sticky, or hard and crusty?
• has the plant been exposed to any sprays, either deliberately in terms of pesticide treatment or unintentionally, such as drift from another type of product used nearby?
• when did these symptoms appear? (both the white residue and the leaf holes/ragged edges)

Check underneath several leaves and see if you notice any brownish or whitish specks (about the size of a poppy seed or sesame seed) that rubs off with a fingernail. Some insect pests feed while attached to the underside of foliage and aren't always visible on the top side. The patchy yellowing spots on various leaves suggests a pest may be present, but other factors might be causing those symptoms as well, so inspecting the leaf undersides will help rule them out.

If you need to send in more than three images, you can reply more than once in order to upload additional pictures.

Miri

Thank you for the additional photos. Unfortunately, they are too small and not clear enough for us to see details. If you can, please try to send closer/clearer images. 

Maybe we can hone in further with a few more questions. Can you tell us please:

• Does the black and white substance on the underside of the leaf fell crusty? Or is it soft, fluffy, squishy? Can you rub it off with your fingers or does it feel embedded in the leaf?
• How much of the plant is affected by the substance on the leaves? Just a few leaves or all throughout the whole plant?
• Can you cut open one of the affected fruits and see if there is anything (insect?) inside?
• Is the plant growing outdoors year-round in Montgomery County, Maryland or is it in another location? 

Christa

Hello Cecilia,

Unfortunately we did not receive your lemon question replies, so could you please try re-sending?

With regards to your follow-up question, it's hard to make generalizations between unrelated species about difficulties in getting plants to re-bloom. A lot of the factors to consider depend on the plant in question. African Violets, for instance, tend to be eager rebloomers, but may suffer damage from a pest like blossom thrips, disease like powdery mildew, over-watering root rot, over-fertilizing root burn, or too-low temperatures or humidity levels. Orchids like Phalaenopsis need a temperature drop of about 15-20 degrees between daytime highs and nighttime lows to help initiate the development of flower spikes. For many orchids, an additional bloom trigger is photoperiod - the relative length of light versus darkness over the course of a day - and this seasonality is what brings them into bloom at certain times of year. Bright indoor lighting after sunset close to the plants may be throwing-off their measurement of time and postponing bloom.

Hydrangeas are not common indoor pot-plants because they need more light to support good growth, plus a winter dormancy to help "reset" their blooming and growth cycle. When used indoors they are often considered disposable, or are planted outside when one is finished enjoying the forced blooms. Unfortunately for people planting them outside afterwards and hoping for a yearly return of flowers, the varieties used for forcing are not reliably bud-hardy and may survive but not rebloom well in future years because their flower buds didn't survive the winter. The best alternative is to select only those Hydrangea varieties with proven hardiness which are sold as outdoor garden shrubs. If a plant is in that category and still not reblooming well, the usual causes are late frosts damaging the buds that have started growth earlier in spring or loss of the buds due to ill-timed pruning or deer nibbling.

Over-fertilizing plants can cause damage to sensitive roots and may lead to more foliage growth at the expense of flowers, though this can vary from species to species because their nutrient needs are different. Many factors influence how quickly or slowly a potted plant runs low on nutrients, like type of potting mix, watering frequency, light levels, and growth rate. Fertilizer ratios with a higher phosphorus [P] level than its nitrogen [N] level might help promote bloom, but not by itself - other growth-promoting factors like lighting, temperature, humidity, and moisture levels all impact how well a plant can make use of those nutrients. Environmental conditions work in concert to support healthy, normal plant growth and blooming.

Miri

We see your answers now, thank you.

Now that we know the plant is not local, we cannot determine what the cause is of the lemon's symptoms. Despite any similarities in climate, the specific range of insects, diseases, and other environmental factors impacting the plant's health are not identical. We do not have expertise with pathogens or pests of citrus that occur in Argentina. In this case, it would be best for yourself or someone in that area to reach-out to educators or agricultural specialists there for help in diagnosis.

Miri