Answer: If it looks like foam or spit, the problem is with pests called spittlebugs. They are very small sucking insects and they cover themselves with foam to ward off predators. Under their protective covering they feed by sucking the juices from plant stems. You can hose these pests off with a strong stream of water or pinch them off your plants. Do this as soon as you see the spittle and you'll keep the population down to a tolerable number.
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