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I have a cranberry tree in a planter, and today I noticed this white and yellow stuff in the soil. Here are some pics of the soil: enter image description here enter image description here

A few months ago this same plant had tons of scale, and I cleaned it up well. These are some pics from many months ago of the scale (pic1 & pic2). It's improved since that time and it's been growing lots of new leaves, but today I noticed this white and yellow stuff in the soil. It also has some ants, and it still has scale (although it's very little..

What can I do get rid of this stuff? My concern is that this is not letting the plant grow cranberries.

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The white and yellow stuff on the soil are a combination of fungal growth and slime mould, likely caused by the soil in the pot being too wet for too long. The yellow growth appears to be an early stage Fuligo septica, common name dog's vomit slime mould, more info here https://wimastergardener.org/article/dog-vomit-slime-mold-fuligo-septica/. These types of growth occur on soil which has wood debris within it, but only if the soil/woody content is very wet. Neither of these will trouble the plant growing in the soil, but the soil being too wet all the time will cause some problems for the plant.

Allow the soil to dry out a little and don't keep it so wet; as the soil dries, these growths will disappear. Hopefully there is drainage in the pot in the form of holes at the base - check these are open and working properly so that water can get out. If there are no drainage holes, find a pot which does have holes and move into that. If you have the pot standing in a tray, remove that so the plant is not left sitting in water.

You mention ants; if you mean ants on the plant itself, they are likely there to harvest honeydew from either scale or aphid infestation - get rid of those and the ants will disappear. Whilst ants can and do make their nests inside pots, it is unlikely in this case because the soil is too wet - ants like much drier conditions.

  • Thank you. What do you recommend to permanently eliminate scale? – rbhat Sep 29 '19 at 13:55
  • Found this on cranberry scale specifically - its really aimed at professional growers, but it might point you in the right direction to select an effective treatment pnwhandbooks.org/insect/small-fruit/cranberry/cranberry-scale – Bamboo Sep 29 '19 at 15:48
  • scale is hard to completely eliminate it require multiple applications of two or more different strategies in rotation over many many many months. Since, their life cycle is complex, you may destroy all the adults laying eggs, but it's hard to kill the eggs. The nymphs or crawlers are the easiest to kills, since they lack any outer protection, with simple insecticidal soap. The problem is they are impossible to see with the naked eye. That is why it takes multiple application of different strategies. – GardenGems Nov 3 '19 at 0:49
  • I think you have a bigger problem other than scale. A healthy outdoor plant rarely gets a huge outbreak of any pest. The plant is obviously under stress from something else. Growers get this problem because the density of monoculture/growing lots of the same plant. I do not recommend using any sprays on your plant unless it is an extreme problem. The outside world is full of predators that should be keeping pest in check. Spraying will kill the natural defender of your plant. Many of the scale will also get killed off during winter. – GardenGems Nov 3 '19 at 1:02

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